Corrected entry: Brundle's steak experiment has one major flaw in its planning: he takes care to separate the two cuts of meat by placing them on different coloured plates so he knows which is the control cut and which is the teleported cut, however he then proceeds to cook them both at the same time in the same pan. Being a scientist you'd think he'd know this could quite easily ruin the results of the experiment as whatever changes occurred to the teleported steak could leak out with its juices and contaminate the control.
Corrected entry: In the scene where Jeff Goldblum starts transforming into the Brundlefly, there is a long sequence where his skin and body parts keep falling off and making a huge mess on the floor. After John Getz blows the creature's telepod power cord apart with a shotgun, he collapses onto the floor which is now clean.
Corrected entry: In the scene where Veronica is interviewing Brundle and turns on the tape recorder, it stops the next minute because the tape ends. When her boss is listening to the tape we can see the tape is at the beginning at that time of the conversation.
Corrected entry: After Seth Brundle has gone through his final stage of metamorphosising into the Brundlefly, he throws Ronnie (Geena Davis) into one telepod and then starts to make his way across the lab towards the other one. Watch as he emerges from behind a wooden pillar, there's one shot where a crew member's arm is seen reaching inside the back of the Brundlefly puppet, to move the creature's head. You'll need to slow-mo to see it but it's there. (As per the rules of this site, visible crew members is an acceptable use of slow motion.)