The team travel to the planet Vis Uban, hoping to find the lost city of the Ancients; instead, they find Daniel Jackson, fully human once again and with no memory of his former life, having spent the last few months living as a simple peasant named "Arrom". As Daniel returns to the SGC to try and remember who he was, Carter and Jonas devise a plan to destroy Anubis's superweapon before he can shift the balance of power in the galaxy any further in his favor.
"Fallen" provides examples of the following tropes:
- Accidental Misnaming: Daniel keeps referring to O'Neill as "Jim", much to his annoyance.
- Air-Vent Passageway: Daniel crawls into one of these on Anubis's ship to hide from his Jaffa.
- All-Loving Hero: Carter describes Daniel this way when he voices his fears that he won't like the person he used to be if he gets his memories back.Carter: You were — you are — brilliant. One of the most caring, passionate... you're the type of person who would give his own life for someone he doesn't even know.Daniel: That doesn't sound so bad.Carter: If you had one fault, it was that you wanted to save people so badly, you wanted to help people so much, that it tore you apart when you couldn't make a difference.Daniel: That actually sounds kinda hard to live up to.
- An Aesop: Discussed when SG-1 meets the elder of the tribe that calls Vis Uban home.Elder: He that has too many friends has none.
O'Neill: Ah, but "birds of a feather"...
Elder: I'm unfamiliar with that story. What lesson does it teach?
- Blind Without 'Em: Implied when Fraiser returns Daniel's glasses to him.Daniel: Wow. That's different.O'Neill: You recognize me now?
- The Bus Came Back: Daniel returns after having spent the last season ascended to a higher plane of existence.
- Continuity Nod:
- The gate address for Vis Uban is the last of the addresses that O'Neill added to the system after receiving the Ancient repository of knowledge.
- Carter mentions that they know from previous experience that an ascended being can choose to re-take human form.
- After seeing a picture of O'Neill's son in his locker, Daniel remembers that his death is the reason they met in the first place, as O'Neill signed up for the original trip to Abydos believing that it would be a suicide mission.
- At the end of the episode, Anubis approaches Jonas with the same mind probing device that he used on Thor in "Revelations".
- Crazy Enough to Work: Carter's plan to destroy Anubis's superweapon, which involves her and O'Neill flying an X-302 through his defense shields with a short-range Hyperspace Ambush, among other things.O'Neill: All I'm saying, just for the record: this is the wackiest plan we've ever come up with.Carter: Wackier than strapping an active stargate to the bottom of the X-302?O'Neill: Oh, yeah.O'Neill: (walking out the door) Yep!Carter: (to Daniel and Jonas) ...He's probably right.
- De-Power: Daniel is a regular old human once again. Carter speculates that this is his punishment for breaking the rules of the ascended in trying to take out Anubis.
- Deadpan Snarker: Jonas comments on the fact that Daniel seems to default back into snark mode remarkably quickly as they try to hack into Anubis's systems.Jonas: Okay, do some kind of, uh, keyword search?Daniel: Yeah, for what, "Achilles"?Jonas: Oh, that's good. I'm glad to see your memory's finally coming back, not to mention your razor-sharp wit.
- Distressed Dude: Jonas is captured by Anubis's forces while on board the mothership.
- Does This Remind You of Anything?: During Carter's Exposition about a ventilation shaft that cools the main weapon on Anubis' flagship, O'Neill interrupts with "Where exactly is this...shaft, exactly?"
- Dragon-in-Chief: Lord Yu's First Prime, Oshu, starts covertly taking charge of Yu's fleet as he slips further into senility.
- Eureka Moment: Jonas has one at the beginning of the episode when he realizes that the "lost city" is actually "the city of the lost", prompting an excited dash through the SGC to find Carter and share his discovery.
- Fakin' MacGuffin: Jonas comes up with a plan to create a fake version of Ancient tablet to lure Anubis to Vis Uban so that the team can try to disable his superweapon while he's distracted.
- Figure It Out Yourself: O'Neill declines to tell Daniel any details of his former life when asked, wanting him to remember of his own accord.
- Forgot the Call: Daniel has spent the last two months or so living a simple pastoral life on Vis Uban, having forgotten both his place on SG-1 and the fact that he spent the last year as a powerful Energy Being.
- Frontline General: Hammond goes through the gate to establish a Mission Control center on Vis Uban to coordinate with the team during their attack on Anubis's mothership.
- Generic Doomsday Villain: O'Neill's description of Anubis:O'Neill: Kind of an over-the-top, cliche bad guy. Black Cloak, oily skin, kinda spooky.
- Hard-Work Montage: Happens as the team plus Daniel and a handful of Tok'ra start setting up their plan to attack Anubis.
- Hurricane of Aphorisms: O'Neill and the elder of the nomadic tribe on Vis Uban have some fun trading pithy sayings back and forth.Shamda: No-one can be a friend if you know not whether to trust them.O'Neill: Don't judge a book by its cover.Shamda: Enemies' promises were made to be broken.O'Neill: And yet, honesty is the best policy.Shamda: He that has too many friends has none.O'Neill: Ah, but birds of a feather.Shamda: I'm unfamiliar with that story. What lesson does it teach.O'Neill: It has to do with flocking, and togetherness... and... to be honest, I'm not that familiar with the particulars myself.
- I'm Not a Doctor, but I Play One on TV:Khordib: (about Teal'c) He is Jaffa.O'Neill: No, but he plays one on TV.
- Just Friends: After Carter spends several minutes delivering a fairly glowing appraisal of Daniel's character to try and convince him to go back to Earth with them, he asks if there was ever anything between them. Carter responds that they were just "really, really good friends".
- Loophole Abuse: Teal'c speculates that Oma Desala may have deliberately exploited a loophole in the rules of the ascended by ensuring that Daniel will recover his memories in time.
- Meaningful Name: The nomads living on Vis Uban explain that since Daniel couldn't remember his own name, they christened him "Arrom", meaning "naked one", due to the state they found him in.
- Mind Probe: Anubis prepares to use one on Jonas as the episode ends.
- Naked on Arrival: Daniel is dumped on Vis Uban sans clothing after his return to mortal form in The Teaser.
- Oblivious Guilt Slinging: Daniel excitedly telling Teal'c that he remembers Sha're, and then talking about how much he loved her after realizing that she's dead, totally unaware that Teal'c is the one who killed her.
- Old-School Dogfighting: O'Neill and Carter in a single X-302 versus several of Anubis's Death Gliders.
- Pragmatic Villainy: Much of Carter's plan hinges on Yu providing backup as he has done in the past due to his opposition to Anubis; unfortunately, his increasing senility proves to be a spanner in the works that she hadn't accounted for.
- Shout-Out: The scenes of O'Neill and Carter in the X-302 destroying Anubis's power core and the planning of the mission at the SGC are full of references to Star Wars episode four and six. O'Neill Lampshades this during the X-302 pre-flight.O'Neill: I thought we were going with "Red Leader" on this one.
- We Do the Impossible: Summed up in this exchange, after Carter has finished outlining her plan:O'Neill: Okay, everyone who thinks this is absolutely an insane idea, raise your hand. Come on, be honest, let's go.(Everybody in the room raises their hand, including Carter herself)Hammond: Keep your hands up, people, because the next question is "who's going to make this happen?"(Everybody's hands remain in the air)