When Dag and her two pals enter the School, after speaking with the School Girl, it's plain day light. When they leave after the interview with the School Principal that took about 5 minutes, it's pitch dark night outside. (72 of 85 minutes in the VHS version).
Every time they get onto the bikes, Dag's clothes change. They obviously shot all of the "riding" scenes at once and just inserted them where need be, without worrying about the clothes matching up.
The purple extended-fork chopper Dag keeps working on to prepare for her vengeance ride is not the same bike she's riding in the rest of the movie.
When Bernie comes to Dag's house with the carburetor, the boom mic is visible in the lower left corner of the frame. The camera operator quickly zooms in to take it out of the shot.