Is there an issue? Send a MessageReason:
None
Added DiffLines:
* HarsherInHindsight: While Sara's chewing out Barry for saving his mother was already divisive enough at the time, during a later crossover when [[spoiler: Oliver]] dies, she has absolutely no problem with dropping everything to find a Lazarus Pit (despite having never put in any effort to resurrect Laurel).
Is there an issue? Send a MessageReason:
None
Changed line(s) 8 (click to see context) from:
** Cisco telling Felicity that no matter how bad Barry feels for Dante's death it's not going to change things, and that Barry shouldn't be held up on a pedestal since he can make mistakes like everyone else. Every character blowing up in Barry's face also counts.
to:
** Cisco telling Felicity that no matter how bad Barry feels for Dante's death death, it's not going to change things, and that Barry shouldn't be held up on a pedestal since he can make mistakes like everyone else. Every character blowing up in Barry's face also counts.
Is there an issue? Send a MessageReason:
Removing blatant copy pasted entries, and ones from the Supergirl episode, since that isn’t technically part of the crossover.
Deleted line(s) 1 (click to see context) :
* AssPull: Eliza being able to cure J'onn of becoming a White Martian with TheVirus (which was engineered to destroy entire species with the exclusion of one, but is able to be customized to the degree of attacking only the cells of a specific species) as he only found out he was turning into one in the previous episode. It seems like he was cured so that the writers could wrap up the plot until the mid-season premiere and give Kara one less thing to worry about so that she can go to Barry's universe.
Deleted line(s) 8 (click to see context) :
* CaptainObviousReveal: Lena turning out to be a FakeDefector, after everything before has made her out to be the WhiteSheep of the Luthor family.
Changed line(s) 14 (click to see context) from:
* ContinuityLockout: If you don't watch the other three shows you likely will have no clue what's going on.
to:
* ContinuityLockout: If you don't watch the other all three shows you likely will have no clue what's going on.
Deleted line(s) 17,18 (click to see context) :
* LikeYouWouldReallyDoIt: After all the hell this crew got over killing off Sara Lance, there's no way they'd [[BuryYourGays fridge Maggie like this]]. (Especially given that, in 2016, the BuryYourGays trope had become extremely controversial.)
* MoralEventHorizon: While Cadmus (Lillian and Hank, essentially) have done awful things this whole season, their FinalSolution plot is a new moral low.
* MoralEventHorizon: While Cadmus (Lillian and Hank, essentially) have done awful things this whole season, their FinalSolution plot is a new moral low.
Changed line(s) 26,27 (click to see context) from:
* StrawmanHasAPoint: Zor-El creating the Medusa bioweapon is supposed to be seen as a bad thing, considering that he becomes a BrokenPedestal for Kara, but his arguments that it's a perfect defensive weapon that can save Kryptonian lives hits the nail on the head. In case of an invasion they would have to defend themselves somehow anyway, most likely using lethal force, and Medusa could win the war quickly and without risking military or civilian casualties. Granted it could be used for genocide, or against ''them'' if it ever fell into the wrong hands, but that's the problem for ''any'' weapon, and certainly what Cadmus did was not how Zor-El intended Medusa to be used. Additionally, in the crossover, Kara reveals that the Dominators have attacked Krypton in the past, killing many people, so there's precedent for Zor-El's fears.
* SurprisinglyImprovedSequel: Compared to ''Series/{{Arrow}}''[='=]s side of the {{Crossover}} from [[Series/HeroesJoinForces the previous year]], this was is character driven and has "drama done right".
* SurprisinglyImprovedSequel: Compared to ''Series/{{Arrow}}''[='=]s side of the {{Crossover}} from [[Series/HeroesJoinForces the previous year]], this was is character driven and has "drama done right".
to:
Deleted line(s) 35 (click to see context) :
** J'onn getting cured at the end of the episode wastes a good plot that could have had him become a White Martian and learn from the experience that not all of them are naturally evil, or basically challenge his hatred of them.
Deleted line(s) 40 (click to see context) :
** Barry not being able to assist Supergirl with the Cadmus conflict as him coming out the breach and punching Henshaw would have been a better start to the crossover than just appearing at the end. Though him not being included could be justified as he would have been able to help resolve the conflict quicker because of him not being an alien and so he wouldn't have had to worry about Medusa killing him.
Is there an issue? Send a MessageReason:
Requires Word Of God confirmation
Deleted line(s) 2,4 (click to see context) :
* AuthorsSavingThrow:
** The implications that Oliver is still in love with Laurel, and the fact that ''Laurel'', not Felicity, is his ideal lover in the LotusEaterMachine, is this for those who felt that [[FanPreferredCouple Oliver should've ended up with Laurel instead]], especially after Felicity adopted the many traits Laurel had in Seasons 1 and 2 that made their initial romance so hated during her romance with Oliver.
** Cisco, who has been holding a blind grudge against Barry for creating Flashpoint and unintentional causing his brother's death, experiences the same guilt after realizing that he is one of the factors that brought the Dominators to Earth by altering the timeline. This is what gets him to finally forgive Barry.
** The implications that Oliver is still in love with Laurel, and the fact that ''Laurel'', not Felicity, is his ideal lover in the LotusEaterMachine, is this for those who felt that [[FanPreferredCouple Oliver should've ended up with Laurel instead]], especially after Felicity adopted the many traits Laurel had in Seasons 1 and 2 that made their initial romance so hated during her romance with Oliver.
** Cisco, who has been holding a blind grudge against Barry for creating Flashpoint and unintentional causing his brother's death, experiences the same guilt after realizing that he is one of the factors that brought the Dominators to Earth by altering the timeline. This is what gets him to finally forgive Barry.
Is there an issue? Send a MessageReason:
None
Changed line(s) 45 (click to see context) from:
** Nate and Amaya not appearing. While it makes sense for someone to look after the Waverider, it would have been awesome for them to team up with Oliver and Barry when the other heroes were under MindControl. Especially since we didn't get the opportunity to see Amaya go against Kara as naturally because of Amaya's powers being magical she could have put up a decent fight against her since kryptonians are vulnerable to magic.
to:
** Nate and Amaya not appearing.appearing in the first part of the crossover. While it makes sense for someone to look after the Waverider, it would have been awesome for them to team up with Oliver and Barry when the other heroes were under MindControl. Especially since we didn't get the opportunity to see Amaya go against Kara as naturally because of Amaya's powers being magical she could have put up a decent fight against her since kryptonians are vulnerable to magic.
Is there an issue? Send a MessageReason:
None
Deleted line(s) 19 (click to see context) :
* EvenBetterSequel: To the [[Series/FlashVsArrow previous]] [[Series/HeroesJoinForces two]] crossovers since this one handles the characters properly and doesn't have the baggage of being a PoorlyDisguisedPilot.
Changed line(s) 33 (click to see context) from:
** Iris' job is to report on things going on in Central City, and yet during the scene where all of the reporters are gathered in a press conference held by the new President, she is nowhere to be found. Fans are particularly irate because this is the third crossover in a row where Iris hasn't been involved outside of the ''Flash'' episode.
to:
** Iris' job is to report on things going on in Central City, and yet during the scene where all of the reporters are gathered in a press conference held by the new President, she is nowhere to be found. Fans are particularly irate because this is the third crossover in a row where Iris hasn't been involved outside of the ''Flash'' episode.episode, and because yet another chance to address her journalism was neglected.
Is there an issue? Send a MessageReason:
Flame Bait and not YMMV
Deleted line(s) 20,23 (click to see context) :
* ForgottenPhlebotinum: The whole reason they made a super suit for Barry was that the air friction of super speed was burning holes in his clothes. Wally is out-running early Barry's speed handily, but has neither a super suit nor burnt clothes.
* InternetBackdraft:
** The advertising made a big deal of the '''four-part''' "Heroes vs. Aliens" crossover beginning with Supergirl. Turns out the Supergirl installment was limited to Barry and Cisco coming to get Kara at the end and the entire scene was shown ''again'' in the ''Flash'' installment, making its inclusion in this episode completely pointless. Though the producers had revealed this was the case before the season even started, likely to offset this very thing. Also, thematically, "Medusa" ends up being a bookend to the finale of the crossover as it also deals with human distrust of aliens and a bioweapon that targets a specific group for extermination.
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped from killing Darhk by the forceful intervention of her teammates.
* InternetBackdraft:
** The advertising made a big deal of the '''four-part''' "Heroes vs. Aliens" crossover beginning with Supergirl. Turns out the Supergirl installment was limited to Barry and Cisco coming to get Kara at the end and the entire scene was shown ''again'' in the ''Flash'' installment, making its inclusion in this episode completely pointless. Though the producers had revealed this was the case before the season even started, likely to offset this very thing. Also, thematically, "Medusa" ends up being a bookend to the finale of the crossover as it also deals with human distrust of aliens and a bioweapon that targets a specific group for extermination.
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped from killing Darhk by the forceful intervention of her teammates.
Is there an issue? Send a MessageReason:
None
Changed line(s) 23 (click to see context) from:
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped from Darhk by the forceful intervention of her teammates.
to:
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped from killing Darhk by the forceful intervention of her teammates.
Is there an issue? Send a MessageReason:
None
Changed line(s) 23 (click to see context) from:
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped by the forceful intervention of her teammates.
to:
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped from Darhk by the forceful intervention of her teammates.
Is there an issue? Send a MessageReason:
Shamelessly copied as much entries as I can from the recap pages.
Added DiffLines:
* AssPull: Eliza being able to cure J'onn of becoming a White Martian with TheVirus (which was engineered to destroy entire species with the exclusion of one, but is able to be customized to the degree of attacking only the cells of a specific species) as he only found out he was turning into one in the previous episode. It seems like he was cured so that the writers could wrap up the plot until the mid-season premiere and give Kara one less thing to worry about so that she can go to Barry's universe.
* AuthorsSavingThrow:
** The implications that Oliver is still in love with Laurel, and the fact that ''Laurel'', not Felicity, is his ideal lover in the LotusEaterMachine, is this for those who felt that [[FanPreferredCouple Oliver should've ended up with Laurel instead]], especially after Felicity adopted the many traits Laurel had in Seasons 1 and 2 that made their initial romance so hated during her romance with Oliver.
** Cisco, who has been holding a blind grudge against Barry for creating Flashpoint and unintentional causing his brother's death, experiences the same guilt after realizing that he is one of the factors that brought the Dominators to Earth by altering the timeline. This is what gets him to finally forgive Barry.
* BaseBreakingCharacter:
** Cisco, in continuation from the last episode. Some don't agree with his {{jerkass}} behavior and how he ends up making the team question Barry as a leader because of his insistence that he tell them about the secret message[[note]]Especially considering other characters also knew and didn't tell, and it's not Barry's secret or team[[/note]], and believe he should just forgive Barry already. Others feel it is realistic for him to still be angry at Barry over Dante. Then a third camp understands Cisco being angry, but feel that doesn't justify the way he is acting.
** Iris and Joe's MyBelovedSmother treatment of Wally and trying to keep him out of loop also didn't go over with some viewers. Some empathize with their concerns while others were quick to point out the DoubleStandard in their [[NotNowKiddo treatment of Wally.]]
* BrokenBase:
** Bringing the consequences of "Flashpoint" into the mix. Some fans are happy that Barry's dirty laundry has been aired to all his friends and allies (especially John learning he had a daughter); others are annoyed at how Barry's mistakes are being brought up all the time now, that [[{{Hypocrite}} the Legends are in no position to criticize him]] and feel like it's a distraction from moving forward.
** Related to Flashpoint, there is some debate over Diggle's reaction over Baby Sara. Some feel he shouldn't have gotten that upset because of him still having a child just of a different gender and he never would have known of her existence if Barry didn't tell him. While most feel it was a realistic and understandable reaction for a father to find out he had a child that ceased to exist and technically died.
* CaptainObviousReveal: Lena turning out to be a FakeDefector, after everything before has made her out to be the WhiteSheep of the Luthor family.
* CatharsisFactor:
** Cisco telling Felicity that no matter how bad Barry feels for Dante's death it's not going to change things, and that Barry shouldn't be held up on a pedestal since he can make mistakes like everyone else. Every character blowing up in Barry's face also counts.
** On the other hand, Oliver telling Barry that not every little thing that happened because of Flashpoint is his fault by mentioning Season 2's events and how his own father died in a similar vein to his origin also helps those who feel Cisco is beating Barry up too much. Especially since he points out that everyone else changes the future all the time, and nobody even knows whether these particular changes were actually Barry's doing.
** After running into so many villains that are as powerful as her if not more so, it's nice to see Supergirl kicking the rest of the team's ass and reminding the audience how absurdly powerful Kryptonians are.
** Cisco ''finally'' forgiving Barry in the last part and calls him his friend again. What prompts him to do this? [[{{Irony}} Doing the exact same thing he was mad at Barry for doing: altering time.]]
* ContinuityLockout: If you don't watch the other three shows you likely will have no clue what's going on.
* EnsembleDarkhorse: Laura Washington aka Cyberwoman quickly became popular due to her being portrayed by Erica Lutrell from ''WesternAnimation/StevenUniverse''.
* EvenBetterSequel: To the [[Series/FlashVsArrow previous]] [[Series/HeroesJoinForces two]] crossovers since this one handles the characters properly and doesn't have the baggage of being a PoorlyDisguisedPilot.
* ForgottenPhlebotinum: The whole reason they made a super suit for Barry was that the air friction of super speed was burning holes in his clothes. Wally is out-running early Barry's speed handily, but has neither a super suit nor burnt clothes.
* InternetBackdraft:
** The advertising made a big deal of the '''four-part''' "Heroes vs. Aliens" crossover beginning with Supergirl. Turns out the Supergirl installment was limited to Barry and Cisco coming to get Kara at the end and the entire scene was shown ''again'' in the ''Flash'' installment, making its inclusion in this episode completely pointless. Though the producers had revealed this was the case before the season even started, likely to offset this very thing. Also, thematically, "Medusa" ends up being a bookend to the finale of the crossover as it also deals with human distrust of aliens and a bioweapon that targets a specific group for extermination.
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped by the forceful intervention of her teammates.
* LesYay: Sara's comment on Supergirl effortlessly overpowering everyone else in a training session is "It's kinda hot."
* LikeYouWouldReallyDoIt: After all the hell this crew got over killing off Sara Lance, there's no way they'd [[BuryYourGays fridge Maggie like this]]. (Especially given that, in 2016, the BuryYourGays trope had become extremely controversial.)
* MoralEventHorizon: While Cadmus (Lillian and Hank, essentially) have done awful things this whole season, their FinalSolution plot is a new moral low.
* {{Narm}}:
** Thea refusing to leave the LotusEaterMachine for about ten seconds before changing her mind. It appears to only exist because they needed some kind of dramatic act break.
** Wild Dog blaming Supergirl's appearance for the Dominators' appearance, despite the fact that she was brought to their Earth to stop the Dominators ''after'' the heroes ended up finding out about their existence.
** Related to both of the above, Wild Dog's grudge against superpowers lasts for pretty much no time and is resolved ridiculously easily. This is compounded by the fact that [[CompressedVice he didn't seem to have any problem working with Ragman]].
** The scene where all of Oliver's dead loved ones appear to encourage him to leave and be strong – while touching and emotional – seems rather out of place given that he was already leaving, and the world is supposed to be engineered to ''prevent him'' from leaving.
* PortmanteauCoupleName: Skirtwave, as Kara and Rory shippers were born after Heat Wave's "Hey Skirt, call me" line near the end of the episode.
* SpecialEffectsFailure: Tommy and Roy's "ghosts" that appear before Oliver leaves through the portal are obviously C.G.I used from old footage as their actors were unavailable.
* StrawmanHasAPoint: Zor-El creating the Medusa bioweapon is supposed to be seen as a bad thing, considering that he becomes a BrokenPedestal for Kara, but his arguments that it's a perfect defensive weapon that can save Kryptonian lives hits the nail on the head. In case of an invasion they would have to defend themselves somehow anyway, most likely using lethal force, and Medusa could win the war quickly and without risking military or civilian casualties. Granted it could be used for genocide, or against ''them'' if it ever fell into the wrong hands, but that's the problem for ''any'' weapon, and certainly what Cadmus did was not how Zor-El intended Medusa to be used. Additionally, in the crossover, Kara reveals that the Dominators have attacked Krypton in the past, killing many people, so there's precedent for Zor-El's fears.
* SurprisinglyImprovedSequel: Compared to ''Series/{{Arrow}}''[='=]s side of the {{Crossover}} from [[Series/HeroesJoinForces the previous year]], this was is character driven and has "drama done right".
* TheyWastedAPerfectlyGoodCharacter: A couple of examples:
** Iris' job is to report on things going on in Central City, and yet during the scene where all of the reporters are gathered in a press conference held by the new President, she is nowhere to be found. Fans are particularly irate because this is the third crossover in a row where Iris hasn't been involved outside of the ''Flash'' episode.
** Moreover, lots of fans are confused as to why characters from the other shows seem to be more involved than the Legends are, with the episode ending on Barry and Oliver; the Legends are mostly used as supporting characters for them.
** The members of Team Flash and Arrow who don't appear in this episode and helped out in the last two, not being at the victory party at the end. Specifically Iris and Joe not being there when Barry attempted to sacrifice himself to the Dominators.
** Slade is the only returning BigBad who has no lines whatsoever and whose face is kept hidden, for the obvious reason that his actor Creator/ManuBennett didn't reprise the role.
** Cyberwoman could've made more of a threat if she hadn't debuted in a crossover involving aliens and where she's [[CurbStompBattle curb stomped]] by Flash and Supergirl in a matter of minutes. Given that she's also an Expy of [[ComicBook/TeenTitans Cyborg's]] [[EvilCounterpart Evil Distaff Counterpart]] Cyborgirl, some feel he should've been introduced before including her in any capacity.
* TheyWastedAPerfectlyGoodPlot:
** J'onn getting cured at the end of the episode wastes a good plot that could have had him become a White Martian and learn from the experience that not all of them are naturally evil, or basically challenge his hatred of them.
** Barry and Cisco only recruiting Kara to help them in the crossover event, as it would have been interesting to have J'onn go with them as well as his powers could benefit in the battle and just to see how characters like Diggle would react to not just Kara but him. It generally would also be cool for Alex, Winn, and James to meet Team Arrow and Team Flash.
*** Also Superman not being part of the crossover, as he is in Metropolis.
*** And Alex could have gotten to talk with Sara about her newly discovered sexuality.
*** Though overall their absence in the crossover event is justified by the fact that the DEO stills needs people to run it in Kara's temporary absence along with needing J'onn and his abilities. Then in regards to Alex she has just entered a relationship with Maggie at the end of this episode and generally Alex, J'onn, and the others have no obligation to risk their lives for another Earth while Kara is mostly going because of a favor she owns to Barry. Then given the urgency of the crossover invasion plot, there wouldn't be enough time for everyone to get to know each other.
** Barry not being able to assist Supergirl with the Cadmus conflict as him coming out the breach and punching Henshaw would have been a better start to the crossover than just appearing at the end. Though him not being included could be justified as he would have been able to help resolve the conflict quicker because of him not being an alien and so he wouldn't have had to worry about Medusa killing him.
** Those who were hoping that Barry would meet J'onn or that Wally (who has a BigDamnHeroes moment) would join the team as Kid Flash are going to be disappointed.
** Nate and Amaya not appearing. While it makes sense for someone to look after the Waverider, it would have been awesome for them to team up with Oliver and Barry when the other heroes were under MindControl. Especially since we didn't get the opportunity to see Amaya go against Kara as naturally because of Amaya's powers being magical she could have put up a decent fight against her since kryptonians are vulnerable to magic.
** Kara contacting Clark and having Superman himself help the others would also have been awesome. Or that "[[Franchise/{{Batman}} Vigilante]]" her cousin teamed up with.
** Jay Garrick / The Flash has been watching over Barry, so seeing him team up with Barry and all the other heroes to fight off this invasion would've been cool.
* WinBackTheCrowd: The ''Arrow'' episode proved largely popular, due to the returning characters (especially Laurel), its connections to the other series as part of the 2016 crossover, and its retrospective nature.
----
* AuthorsSavingThrow:
** The implications that Oliver is still in love with Laurel, and the fact that ''Laurel'', not Felicity, is his ideal lover in the LotusEaterMachine, is this for those who felt that [[FanPreferredCouple Oliver should've ended up with Laurel instead]], especially after Felicity adopted the many traits Laurel had in Seasons 1 and 2 that made their initial romance so hated during her romance with Oliver.
** Cisco, who has been holding a blind grudge against Barry for creating Flashpoint and unintentional causing his brother's death, experiences the same guilt after realizing that he is one of the factors that brought the Dominators to Earth by altering the timeline. This is what gets him to finally forgive Barry.
* BaseBreakingCharacter:
** Cisco, in continuation from the last episode. Some don't agree with his {{jerkass}} behavior and how he ends up making the team question Barry as a leader because of his insistence that he tell them about the secret message[[note]]Especially considering other characters also knew and didn't tell, and it's not Barry's secret or team[[/note]], and believe he should just forgive Barry already. Others feel it is realistic for him to still be angry at Barry over Dante. Then a third camp understands Cisco being angry, but feel that doesn't justify the way he is acting.
** Iris and Joe's MyBelovedSmother treatment of Wally and trying to keep him out of loop also didn't go over with some viewers. Some empathize with their concerns while others were quick to point out the DoubleStandard in their [[NotNowKiddo treatment of Wally.]]
* BrokenBase:
** Bringing the consequences of "Flashpoint" into the mix. Some fans are happy that Barry's dirty laundry has been aired to all his friends and allies (especially John learning he had a daughter); others are annoyed at how Barry's mistakes are being brought up all the time now, that [[{{Hypocrite}} the Legends are in no position to criticize him]] and feel like it's a distraction from moving forward.
** Related to Flashpoint, there is some debate over Diggle's reaction over Baby Sara. Some feel he shouldn't have gotten that upset because of him still having a child just of a different gender and he never would have known of her existence if Barry didn't tell him. While most feel it was a realistic and understandable reaction for a father to find out he had a child that ceased to exist and technically died.
* CaptainObviousReveal: Lena turning out to be a FakeDefector, after everything before has made her out to be the WhiteSheep of the Luthor family.
* CatharsisFactor:
** Cisco telling Felicity that no matter how bad Barry feels for Dante's death it's not going to change things, and that Barry shouldn't be held up on a pedestal since he can make mistakes like everyone else. Every character blowing up in Barry's face also counts.
** On the other hand, Oliver telling Barry that not every little thing that happened because of Flashpoint is his fault by mentioning Season 2's events and how his own father died in a similar vein to his origin also helps those who feel Cisco is beating Barry up too much. Especially since he points out that everyone else changes the future all the time, and nobody even knows whether these particular changes were actually Barry's doing.
** After running into so many villains that are as powerful as her if not more so, it's nice to see Supergirl kicking the rest of the team's ass and reminding the audience how absurdly powerful Kryptonians are.
** Cisco ''finally'' forgiving Barry in the last part and calls him his friend again. What prompts him to do this? [[{{Irony}} Doing the exact same thing he was mad at Barry for doing: altering time.]]
* ContinuityLockout: If you don't watch the other three shows you likely will have no clue what's going on.
* EnsembleDarkhorse: Laura Washington aka Cyberwoman quickly became popular due to her being portrayed by Erica Lutrell from ''WesternAnimation/StevenUniverse''.
* EvenBetterSequel: To the [[Series/FlashVsArrow previous]] [[Series/HeroesJoinForces two]] crossovers since this one handles the characters properly and doesn't have the baggage of being a PoorlyDisguisedPilot.
* ForgottenPhlebotinum: The whole reason they made a super suit for Barry was that the air friction of super speed was burning holes in his clothes. Wally is out-running early Barry's speed handily, but has neither a super suit nor burnt clothes.
* InternetBackdraft:
** The advertising made a big deal of the '''four-part''' "Heroes vs. Aliens" crossover beginning with Supergirl. Turns out the Supergirl installment was limited to Barry and Cisco coming to get Kara at the end and the entire scene was shown ''again'' in the ''Flash'' installment, making its inclusion in this episode completely pointless. Though the producers had revealed this was the case before the season even started, likely to offset this very thing. Also, thematically, "Medusa" ends up being a bookend to the finale of the crossover as it also deals with human distrust of aliens and a bioweapon that targets a specific group for extermination.
** Many fans chaffed at the Legends getting on Barry's case for changing time, since they have their own fair share of screw ups in that area as well (Stein nearly prevented his own marriage after all). Sara in particular comes off as hypocritical by saying she has to resist the temptation to change things to save Laurel when she in fact gave into that temptation twice and was only stopped by the forceful intervention of her teammates.
* LesYay: Sara's comment on Supergirl effortlessly overpowering everyone else in a training session is "It's kinda hot."
* LikeYouWouldReallyDoIt: After all the hell this crew got over killing off Sara Lance, there's no way they'd [[BuryYourGays fridge Maggie like this]]. (Especially given that, in 2016, the BuryYourGays trope had become extremely controversial.)
* MoralEventHorizon: While Cadmus (Lillian and Hank, essentially) have done awful things this whole season, their FinalSolution plot is a new moral low.
* {{Narm}}:
** Thea refusing to leave the LotusEaterMachine for about ten seconds before changing her mind. It appears to only exist because they needed some kind of dramatic act break.
** Wild Dog blaming Supergirl's appearance for the Dominators' appearance, despite the fact that she was brought to their Earth to stop the Dominators ''after'' the heroes ended up finding out about their existence.
** Related to both of the above, Wild Dog's grudge against superpowers lasts for pretty much no time and is resolved ridiculously easily. This is compounded by the fact that [[CompressedVice he didn't seem to have any problem working with Ragman]].
** The scene where all of Oliver's dead loved ones appear to encourage him to leave and be strong – while touching and emotional – seems rather out of place given that he was already leaving, and the world is supposed to be engineered to ''prevent him'' from leaving.
* PortmanteauCoupleName: Skirtwave, as Kara and Rory shippers were born after Heat Wave's "Hey Skirt, call me" line near the end of the episode.
* SpecialEffectsFailure: Tommy and Roy's "ghosts" that appear before Oliver leaves through the portal are obviously C.G.I used from old footage as their actors were unavailable.
* StrawmanHasAPoint: Zor-El creating the Medusa bioweapon is supposed to be seen as a bad thing, considering that he becomes a BrokenPedestal for Kara, but his arguments that it's a perfect defensive weapon that can save Kryptonian lives hits the nail on the head. In case of an invasion they would have to defend themselves somehow anyway, most likely using lethal force, and Medusa could win the war quickly and without risking military or civilian casualties. Granted it could be used for genocide, or against ''them'' if it ever fell into the wrong hands, but that's the problem for ''any'' weapon, and certainly what Cadmus did was not how Zor-El intended Medusa to be used. Additionally, in the crossover, Kara reveals that the Dominators have attacked Krypton in the past, killing many people, so there's precedent for Zor-El's fears.
* SurprisinglyImprovedSequel: Compared to ''Series/{{Arrow}}''[='=]s side of the {{Crossover}} from [[Series/HeroesJoinForces the previous year]], this was is character driven and has "drama done right".
* TheyWastedAPerfectlyGoodCharacter: A couple of examples:
** Iris' job is to report on things going on in Central City, and yet during the scene where all of the reporters are gathered in a press conference held by the new President, she is nowhere to be found. Fans are particularly irate because this is the third crossover in a row where Iris hasn't been involved outside of the ''Flash'' episode.
** Moreover, lots of fans are confused as to why characters from the other shows seem to be more involved than the Legends are, with the episode ending on Barry and Oliver; the Legends are mostly used as supporting characters for them.
** The members of Team Flash and Arrow who don't appear in this episode and helped out in the last two, not being at the victory party at the end. Specifically Iris and Joe not being there when Barry attempted to sacrifice himself to the Dominators.
** Slade is the only returning BigBad who has no lines whatsoever and whose face is kept hidden, for the obvious reason that his actor Creator/ManuBennett didn't reprise the role.
** Cyberwoman could've made more of a threat if she hadn't debuted in a crossover involving aliens and where she's [[CurbStompBattle curb stomped]] by Flash and Supergirl in a matter of minutes. Given that she's also an Expy of [[ComicBook/TeenTitans Cyborg's]] [[EvilCounterpart Evil Distaff Counterpart]] Cyborgirl, some feel he should've been introduced before including her in any capacity.
* TheyWastedAPerfectlyGoodPlot:
** J'onn getting cured at the end of the episode wastes a good plot that could have had him become a White Martian and learn from the experience that not all of them are naturally evil, or basically challenge his hatred of them.
** Barry and Cisco only recruiting Kara to help them in the crossover event, as it would have been interesting to have J'onn go with them as well as his powers could benefit in the battle and just to see how characters like Diggle would react to not just Kara but him. It generally would also be cool for Alex, Winn, and James to meet Team Arrow and Team Flash.
*** Also Superman not being part of the crossover, as he is in Metropolis.
*** And Alex could have gotten to talk with Sara about her newly discovered sexuality.
*** Though overall their absence in the crossover event is justified by the fact that the DEO stills needs people to run it in Kara's temporary absence along with needing J'onn and his abilities. Then in regards to Alex she has just entered a relationship with Maggie at the end of this episode and generally Alex, J'onn, and the others have no obligation to risk their lives for another Earth while Kara is mostly going because of a favor she owns to Barry. Then given the urgency of the crossover invasion plot, there wouldn't be enough time for everyone to get to know each other.
** Barry not being able to assist Supergirl with the Cadmus conflict as him coming out the breach and punching Henshaw would have been a better start to the crossover than just appearing at the end. Though him not being included could be justified as he would have been able to help resolve the conflict quicker because of him not being an alien and so he wouldn't have had to worry about Medusa killing him.
** Those who were hoping that Barry would meet J'onn or that Wally (who has a BigDamnHeroes moment) would join the team as Kid Flash are going to be disappointed.
** Nate and Amaya not appearing. While it makes sense for someone to look after the Waverider, it would have been awesome for them to team up with Oliver and Barry when the other heroes were under MindControl. Especially since we didn't get the opportunity to see Amaya go against Kara as naturally because of Amaya's powers being magical she could have put up a decent fight against her since kryptonians are vulnerable to magic.
** Kara contacting Clark and having Superman himself help the others would also have been awesome. Or that "[[Franchise/{{Batman}} Vigilante]]" her cousin teamed up with.
** Jay Garrick / The Flash has been watching over Barry, so seeing him team up with Barry and all the other heroes to fight off this invasion would've been cool.
* WinBackTheCrowd: The ''Arrow'' episode proved largely popular, due to the returning characters (especially Laurel), its connections to the other series as part of the 2016 crossover, and its retrospective nature.
----
