Alternative Character Interpretation: Done on purpose for the film, where if it was about Stephen and his band trying to make it big but Scott accidentally screws up by being strung on Ramona and they only get successful without him, just like his own ex-girlfriend.
Audience-Alienating Premise: According to this article, that is why the movie didn't do well. The emphasis on the problems of 20-somethings alienated people over 30, the allusions to 80's-90s video games and pop culture alienated most people under the age of 21 (who in most cases wouldn't have been born when the games came out), and Michael Cera has a vocal hatedom.
Probably that song Matthew Patel was singing while he was summoning those demon hipster chicks. In canon, even, it seems.
Stacey:[after Patel breaks into a Bollywood-style number] What?
Even though he was a big deal in the graphic novel, the Nega-Scott came completely out of nowhere in the film, except for an incredibly brief moment of probably the most vague foreshadowing you could do. The deleted scenes on the DVD show Scott seeing Nega-Scott's reflection in the mirror twice. So it looks like there was more foreshadowing planned, it just got cut.
The Prodigy tune "Invaders Must Die" was featured in the trailers and is dangerously catchy.
Many have expressed a weird affection for Matthew Patel's out of nowhere Bollywood-style musical number "Slick" as well.
♪ I'll send you my love on a wire / Lift you up, everytime... ♪
The nightclub fight. From now on, whenever two girls are fighting, try not to imagine that thump thump thump bass beat.
Ending Fatigue: Scott goes to Gideon's club, getting past the bouncers with impromptu passwords. He goes inside and makes amends with his band before beating up Gideon's mooks. Then he has to gain the Power of Love and fight Gideon. After that, Knives and Ramona briefly fight so Scott has to break them up and apologize for being a Jerk Ass. Then Gideon comes back and kills him. He goes through Sub-space, learns of Ramona's control chip, and uses the one-up he earned earlier to come back. He then has to do everything all over again. He gets past the bouncers (this time by punching them instead of going through the passwords), fights off the mooks again, makes amends with his band again, gets the Power of Self Respect, defeats Gideon's demon cheerleaders, beats Gideon, stops a fight between Knives and Ramona again, apologizes for being a Jerk Ass, frees Ramona from Gideon's control, and the three of them beat Gideon again. [deep breath] Then Gideon sends Nega-Scott after him but that "fight" is at least off-camera. After all that, he goes outside to Knives and Ramona and chooses which one he wants to be with. whew. And all of this takes more than quarter of the whole film.
Hype Backlash: Not a huge amount, but at least a number of people have been vocal about their dislike of the film, mostly out of chagrin towards members of the nerd crowd endlessly going on about it being the best movie ever.
MST3K Mantra: If you're thinking hard about the crazy out-of-nowhere Evil Ex fights and unexplained (though consistent) 8/16 bit video game logic, you're doing it wrong. Just lean back and laugh. The relationships between the characters are done completely seriously though.
Jerkass Woobie: Scott. His jerk traits are a lot more visible in the movie, surprisingly. It's (arguably) fairly justified for most of what we see since a lot of it stems from the whole Evil Exes thing.
One-Scene Wonder: The Vegan Police. The exes generally have few scenes. In the strictest sense, Matthew Patel and the Katayanagi Twins qualify; we see a short clip from a Lucas Lee film before his one other scene, and Todd Ingram's scenes all lead directly into one another in a ten-minute sequence.
Relationship Writing Fumble: Scott/Knives ended up becoming one in hindsight; originally, the intended ending was for Scott to get back together with Knives, and her increased role in the film was meant to build up to this. Then Edgar Wright learned of the ending to the comic and ended up changing the ending based off of this. So we're left with all this subtext between Scott and Knives without them becoming a couple again.
Heartwarming in Hindsight: On the home versions, The Scott/Knives pay-off was released as an full alternate cut of the ending!
What an Idiot: Scott gets one from Wallace when Scott gets an email from Matthew Patel, outlining the League of Evil Exes format (Scott dismisses it as rubbish until his fight with Matthew). Granted, when was the last time you took a threat over the internet seriously?
WTH, Casting Agency?: Michael Cera as Scott Pilgrim. Sure, they're both dorky, but Scott is an overly-dramatic, outgoing idiot while Michael Cera is known for playing meek intellectuals, two very different kinds of dork. Bizarrely enough, this decision was made by the author himself.