Because of changes to the script Joss Whedon was forced to make by the studio, he doesn't consider the film canon as established by the TV series. See more...
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Buffy the Vampire Slayer (1992) - 1 major mistake
Continuity: When Buffy is out shopping for her dress and Pike is on his bike beside her, they stop to talk and have an argument. Buffy walks off and Pike turns his bike around to drive off, but as he does this, his bike suddenly moves a few feet away from the wall he was right next to in the previous shot.