Continuity: During the Jacob's Ladder demonstration, the classroom clock remains at 8:10 throughout most of the scene. Then, in several brief flashes, it's 8:15, then 8:10 again, and finally 8:13.

Factual error: In the scene where a bully has been shocked and his heart stops, Powder zaps him back to life. Okay, fine, but as a former ER nurse I noticed some flaws. 1) You can not get a person's heart beating by defibrillating if he's flatlined. You need some sort of activity in the heart first. If Powder had started with some CPR, possibly. 2) Defibrillating someone in a puddle of water? Bad move, unless you assume that Powder's immune to his own shocks. And 3) when defibrillating you hold one paddle on the sternum (middle of the chest) and one on the left side of the ribcage, thus allowing the electricity to go between the paddles and through the heart. The way Powder held his hands really wouldn't have worked.

Continuity: When Jeremy is pulled to a standing position from the bench, notice Powder's jacket collar after her father grabs and then releases him. At first it's up, then it's down and then it's up again.

Continuity: Near the end, when Powder and the girl are sitting at the picnic table, the girl's father runs up and grabs Powder. The girl stands up and steps over the picnic table bench. The scene cuts to a closeup of Powder, then back to a wide scene where the girls is standing up and stepping over the bench again.

Continuity: Jeff Goldblum proudly hypothesises that the reason that Powder has no hair is because he is "living electrolysis". Yeah yeah, he shaved his head and eyebrows but you can clearly see eyelashes and (when the nasty kids strip him off) some curly albino pubes.