Plot hole: When the bullies take revenge on Marty, they doctor the chemicals he is preparing so that they explode. The bullies were punished some time in the afternoon, judging by the sun in the very first shot. Their detention is at 4:30 in the afternoon. Somehow, they manage to acquire the necessary chemicals for the explosion within a couple of hours, even though they are stuck at school. In addition to this, they have no way of knowing what chemicals Marty is preparing, so even if they were able to get chemicals, they would not know which ones to get to destroy his experiment.
Plot hole: In the opening scene, the bullies all go into the girls' toilets with loads of camera equipment, including high tech ones used for proper films and boom mics. This equipment is way too expensive (even more so in the 80s when the film is set) for any high school kid to have.
Trivia: As the directors wanted a well-known actor to play the one adult character (the coach), they initially approached Peter Lawford for the role, but were not able to get him as he wanted $35,000 and a free shopping trip in Harrods, when the most the directors were willing to offer him was $25,000. In the end, one director (Dick Randall) got his friend Marc Smith to play the part for a mere $750.
Question: The bullies think there is a real high school reunion going on. Yet having sat outside the boarded up and abandoned school for 3 hours, they do not seem in the least surprised and begin to doubt a reunion is taking place. They are not suspicious even when they have to break a window to get in to the school.Surely they would be suspicious by then and not go in?swordfish