Martin accidentally views a videotape of Seth Brundle, in which Seth explains his accidental fusion with the fly. However, although the footage comes from The Fly (1986), that particular discussion between Seth and Veronica Quaife was never actually videotaped, unlike the interview with Seth that Martin watches earlier in the film.
When Martin returns to his home, his fridge door is open.
When the apple is scanned in the telepod, the computer recognizes: Loose connective tissue, hyaline, lacuna, chondrocyte, ultrastructure of squamous stratified epithelium. These elements are found only in animals and not in plants, including: cartilaginous tissue and epitelial tissue.
When Martin is in the lab and the security is trying to get in, they have a torch to cut metal to get in. A minute before that, a scientist said there was a conventional door upstairs - a lot easier to break through than the door they were working on.
When Martin and Beth leave Stathis Borans' home, he offers Beth the keys to his Jeep. The car they drive off in is actually a Chevy.
For all intents and purposes, Martin was largely human with dormant mutant genes that would not activate until he matured, however he was given constant injections of allegedly antibiotics but what we later find out to be plain water injected into him. Being a child and having this done on a regular basis would have most likely killed Martin as water would dilute the plasma reducing the ability to carry oxygen around the body.
At the beginning of the movie Veronica is defibrillated, but she still has a strong pulse, of over 100. When her heart stops with the classic beeeeeep, the machine still reads 100beats per minute.
Just after Martin discovers he is being observed and recorded in his private room and is watching the video tapes, he flips through a folder of files - but there is nothing on the pages.
When they try to revive Veronica after the childbirth, they shock her with a defibrillator. Someone holds her hand but doesn't seem affected by it.
As young Martin is investigating Zone 4, the shot dwells on the handle and deadbolt of a door he is about to open. When it opens, you can see the deadbolt is a dummy; there is no actual bolt or latchplate.
Towards the end, Scorby fires his weapon upwards and accidentally kills a co-worker. Prior to that event, the dead body can already be seen in the background.
When MartinFly sprays corrosive vomit in the guard's face, you can hear him scream even though his mouth is closed.
At the beginning of the movie, when Veronica is giving birth to Martin, she is constantly heard screaming. But as the baby is born, reflections from the windows reveal that she has her mouth closed.
Crew guy visible under the table where chrysalis is opened.
When MartinFly throws Dr. Shepard's body, you can see a thick black string pulling it.
Despite the accelerated growth and increased intelligence, Martin was still only 5 years old and would not have had the maturity or understanding of a relationship with a much older woman culminating in them having sex, given that for his whole life he was virtually isolated and only had contact with doctors.
When Martin leaps through the glass in Bay 17 in the film's climax. Beth doesn't scream and freak out over Martin's hideous and terrifying new form and is calm. Although she knows Martinfly is Martin because of the security guard reporting Martin's location to Bartok on the radio, surely Beth would really scream in horror and freak out over Martinfly.