Revealing mistake: Just before Michael and Ellie get out of his car, a fire extinguisher is seen mounted above the dash. Michael opens the hood and the engine begins smoking. Michael reaches into the car for the extinguisher. You can see through the windshield that he is handed another extinguisher instead of removing the one from its mounted spot. The mounted extinguisher is still visible in its holder. Likely done to preserve pacing so he doesn't have to fumble with the clamps on the mounted one.
My Science Project (1985)
1 revealing mistake - chronological order
Directed by: Jonathan R. Betuel
Starring: John Stockwell, Fisher Stevens, Raphael Sbarge, Danielle von Zerneck
Factual error: Harlan's car has a Roots style supercharger. They can't be "turned on and off" as shown. There is no carburettor or fuel injection lines shown between the scoop and the compressor.
Vince Latello: Hey, I hit on Sawyer once.
Michael Harlan: Oh yeah.
Vince Latello: Yeah, I tried to give her this Italian macho bod.
Michael Harlan: What did she do?
Vince Latello: Poor girl lost out. She called me a name I had to look up in the Dictionary.