The alliance between the Adversity Twins and the Sisters, which was the one thing that made the hatred for the twins drop a bit, is thrown out after one episode.
Tom and Jen's interaction with Carrie on the plane to Romania was one of the first team interactions of the season and instigated the Bloggers' plot, and one is left wondering what kind of interaction they could've had if Tom and Jen weren't eliminated in Romania.
The Tennis Rivals getting eliminated before the tennis challenge in "Hello and Dubai".
"I Love Ridonc n Roll" succeeds in wasting two plots in one episode!
The Goths learning to live with each other without makeup. The new outfits they get after that plot's abandoned are also gone by next episode.
Noah deciding to give up on Emma. He's back to being sappy over her next time they meet.
Kitty's selfie skills not coming up during the "Selfie Safari Challenge" in "My Way or Zimbabwe".
Many wanted Kitty to call out her sister Emma for being so rude. What happens instead is that Kitty loses her 'in it for fun' personality (which also comes out of nowhere) just as Emma falls for Noah. Therefore, the roles are reversed but Emma actually calls Kitty out for her previous attitude when her and Noah are being Sickeningly Sweethearts.
Three for the Ice Dancers:
The belief that their luck in many of the early challenges was due to Josee's lucky rabbit's foot charm Bun-Bun which leads into their sideplot of being cursed when she loses it in Romania. Once said curse was lifted, Bun-Bun was never referenced to again.
When they break their curse and resolve to become active villains, they makea changein wardrobe. It disappears without explanation in the next episode.
As the season was coming to an end, several characters who were victims of their nefarious ways (such as Sisters & Goths) commented that karma would eventually get them or express desire in them suffering some form of punishment implying that karma was inevitable. But when they're finally eliminated... Well, nothing major happens to them.
Chet and Lorenzo becoming best friends after hating each other the entire competition. Especially noticeable given the duo lasted half the season yet this only came up one episode before their elimination. Although one could argue their lack of development was what kept them in the game and once they made up, their arc was completed and they no longer had a reason to stay.
The gameplay element of the boomerang, which allows a team to force another team to redo the previous challenge. The idea of a team being forced to go back and do the previous challenge all over again, could have added tension and drama, due to said team having a higher chance of being eliminated. Unfortunately, it's only brought into play in two episodes, both of which end up being non-eliminations, rendering them entirely pointless.
Spud coming into his own as a partner after a half-season of Rock carrying the team.
Bridgette failing to show up (or even get mentioned) in either of the episodes that took place in Australia (where Geoff said she was at in the first episode). A quick cameo or Geoff talking about her more would have been a great way to affirm how things are going between them. Some fans thought that Geoff should have at least mentioned splitting his half of the prize money with Bridgette in the end.
Bridgette not being Geoff's partner for the race. After being the first girl eliminated in both Action and World Tour, many fans wanted Bridgette to get a big comeback of some sort. Ridonculous Race would have been the perfect opportunity for it, showing her and Geoff as a solid contestant duo like they were in Island after their frankly pathetic performance in Action and Bridgette's disastrous and humiliating solo run in World Tour, as well as give both characters and their relationship some much-needed positive development (like the show did with Noah and Owen's friendship). Instead, Geoff's partner is a completely new character who is little more than his stupider clone (making Geoff come off as flat as a result), while Bridgette receives nothing more than a few mentions to justify her absence and remind us that she and Geoff are still together, making her seem like a complete afterthought. Bridgette's absence is particularly egregious since her original voice actress also voiced Carrie.
In "Got Venom" it was revealed that MacArthur is just an alias she used to fake her way into the police academy, and that her real name is Valentina Escobar. Furthermore, she revealed the reason she needed an alias in the first place was that she had a rap sheet a mile long (for everything from illegal fruit smuggling to jaywalking), so it was impossible for her to pass the required background check. After this fact is revealed, it was just as suddenly dropped and neither MacArthur/Valentina nor Sanders mention it outside of a single reference. Word of God has confirmed that the whole thing was simply meant to be a one-time joke.
Kitty losing her 'in it for fun' personality. While it's fine she wanted to take the race seriously, it comes out of nowhere and is more used for Emma losing sight of the race. The only acknowledgement it gets is Emma smugly calling it out when she and Noah are being Sickeningly Sweethearts.
"Ca-Noodling" is the only episode of the season to utilize two new gameplay elements: the "Superteam" where several teams have to work together to proceed and a "Zip-It Ticket" which allows teams who get it to skip remaining challenges and proceed straight to the Chill Zone.
Carrie & Ryan's friendship. It's completely forgotten without explanation in the episode where the latter is eliminated. Some people even wanted them to get together instead.
MacArthur and Brody's Ship Tease, although it did at least get something of a wrap-up at the very last moment when MacArthur hits on Brody but only in the ending where the Surfers win.
