Deliberate mistake: During the fight with Roxy (evil ex number 4), she falls forward before Ramona's leg hits her.
More trailers
More mistakes in Scott Pilgrim vs. the World
Scott Pilgrim: When I'm around you, I kind of feel like I'm on drugs. Not that I do drugs. Unless you do drugs, in which case I do them all the time. All of them.
Trivia: The scene when Ramona delivers the package to Scott and he signs for it, he takes the package and throws it over his shoulder into the trash can, some several feet behind him. In the outtakes reel, they show that no special effects were used. Michael Cera made the shot over his shoulder on his 33rd attempt.