
Plot hole: The whole problem with the teleporter occurs when fly DNA is mixed in with Seth Brundle's DNA, starting his transformation into the Brundlefly. Brundle is on a hiding to nothing from the word go, and the fly is irrelevant. Humans are a walking talking mass of foreign DNA - we are host to one trillion bacteria all of which has a complete complement of DNA, as do various tiny mites that live in our hair follicles and all sorts of single cell organisms in our gut. If the transporter serves to mix the DNA of all living creatures which are in the transporter pod at the time Brundle would turn into a half-man, half-bacteria. Incidentally, DNA from a bacteria, an amoeba or a hair follicle mite would be just as 'compatible' with human DNA as that from an insect. It's quite a simple chemical, really.

Continuity mistake: When swimfan85 is trying to talk to Ben and he tells her he has homework to get done, she is talking with the nick name swimfan85 but when she signs off it says "swimfan has signed off." They forgot to add the 85.

Continuity mistake: When the real 'manager' comes outside to yell at "Mr. O'Donnell', you see the manager walk back into the club. If you look in the background of the next shot, you can see the manager walking through the door again. (00:13:25)

Plot hole: Suzie pulls out some of her teeth with a pair of heavy pliers. This would leave conspicuous tool marks on the teeth that would be visible to the naked eye, let alone under forensic examination. The conclusion would be that Suzie is missing, not dead, and the whole plot would unravel from there.

Revealing mistake: Near the end when Ace gets into his Cadillac, in the first shot facing the front of the car, there is a protective glass in front of Ace (the same width as the windshield) with the dashboard in between that glass and the windshield. Note the vertical edge of the glass is visible at the right side, and the rearview mirror's sticker on the windshield casts a shadow onto the second glass. During the stunt, the flames on the dashboard are between the glass shield and the windshield, keeping the actor safe from harm. (02:46:05)

Continuity mistake: Dick Jones brags (admits?) to Robocop, "I had to kill Bob Morton because he made a mistake. Now, it's time to erase that mistake" while Robocop is crouched on the ground, not only looking away from him from across the room, but also Robocop's eyes are in a vertical position. In the playback, Jones is facing the camera as though it were videotaped or filmed in a studio. (01:10:50 - 01:35:10)

Character mistake: The commentator says "avalanche of power shots by Ivan Drago." Viktor is the one in the ring. Ivan is the father. If you have the subtitles turned on, it even says Viktor in the subtitles instead of the spoken name, Ivan. (00:55:45)

Continuity mistake: When they steal the truck at the mall they have to hot wire it to make it start. Later at the San Andreas fault scene where the road ends, in the same truck, he turns the truck off with the key.

Factual error: Under US law neither Peter Lowenstein nor Oscar Grace would be allowed any level of participation in the investigation, arrest and prosecution of Ned Racine. Both have a highly visible social relationship with him, which disqualifies them from having anything to do with a criminal case against him. In fact as soon as he became a suspect in Edmund Walker's murder they would both be officially 'warned off' - told not to contact him again for any reason.

Plot hole: Patrick Redfern needs someone to be in the boat with him to corroborate his and his wife's deception and be his alibi. That is whole point of his wife lying on beach - he gets this when taking Myra for a ride - but it was portrayed as a random ride she got, he did not intend or plan giving her a ride, he did not see her loitering near the boat, or even in view of him untying the boat. Even if that was intention in the story for him to be seen ready to cast off, the movie viewers did not see her viewing him, only her appearing just before he was set to cast off. Without someone with him the whole deception would not work, he would have no alibi, he could have killed Arlena unseen.

Factual error: The interior shots of the Gemini and Apollo Spacecraft show worn and dirty panels, knobs, switches and circuit breakers. The movie most likely used some original cockpit trainers, but in reality the astronauts were flying brand new spacecraft that were spotless.
Suggested correction: All spacecraft are extensively checked out by technicians before mating to the launch vehicle. Launch rehearsals are done over and over again by both prime and backup crews in the real vehicle in the weeks leading up to launch. Gus Grissom, Ed White, and Roger Chaffee lost their lives in a fire aboard Apollo 1 during one such dress rehearsal. The switches and panels get worn from this use and activity. Crews also make minor modifications to their specific craft to suit the mission and tastes.

Continuity mistake: In one scene after Hutch is beaten up on the bus, he has no facial injuries. Then in the next scene, they are back.

Continuity mistake: Agatha's nightgown strap switches between hanging down on her arm, or being up on her shoulder, normally.

Factual error: Eazy-E sports a black Chicago White Sox hat with a white logo early in the movie in 1986, but the logo didn't officially rollout until 1991.

Factual error: No actor is going to secure a recurring speaking role in a soap opera unless a comprehensive insurance policy has been secured. (This applies to feature films, too.) This will inevitably involve a medical examination. Mr Dorsey's plans are going to become dreadfully unstuck the minute he drops his y-fronts in the doctor's surgery. (No, he can't find a compliant or bribeable doctor - the insurance company will always use their own people.)

Other mistake: After the great fire scene there is a raccoon that drags her baby to shore and begins cleaning it. A few seconds later the baby has jumped across to the other side of his father and siblings, but the mother does not stop licking. This error has since been fixed in newer releases.

Continuity mistake: When Jesse is going to race Johnny Tran at Race Wars for pink slips, and Johnny Tran pulls up in his Honda S2000, Tran has on a black long-sleeved shirt. When the camera goes from side to front view, Tran has on a black tank top. (01:12:41)

Continuity mistake: When Danny & Debbie are having their New Year's dinner at home, the champagne foam instantly disappears in the very next camera angle after pouring it.

Factual error: The lake that Jack told Rose he went ice fishing on when she was threatening to jump is Lake Wissota, a man-made lake in Wisconsin near Chippewa Falls (where Jack grew up). The lake was only filled with water in 1918 when a power company built a dam on the Chippewa River, six years after the Titanic sank. (00:39:05)

Factual error: A force of Russian Tu-22 Backfire bombers attacks the aircraft carrier USS John C. Stennis (CVN-74) by sneaking in under the ship's radar. This is all well and good except that carriers usually don't use their own radar, they have Airborne Early Warning aircraft (E-2 Hawkeye's) that can see much further and not give away the carrier's position (let alone the F-14s which would be patrolling too) not to mention the fleet of destroyers other ships guarding the carrier. The whole point is, the US Navy practiced and planned for such a "carrier versus Backfire" battle for years. I guess in the interest of furthering the plot Hollywood has to ignore the immense measures the USN takes to protect those multi-billion dollar assets, not to mention the 5000+ sailors that man them.
Suggested correction: Being as how the bacteria and mites and such were IN or ON Seth, the machine was able to organize those symbiotic relationships accordingly as teleporting one would teleport all. The fly was separate, not touching. The machine was not programmed to anticipate two separated entities and so combined them into one on the other side.
Phixius ★
We leave behind a vapour trail of bacteria and viruses (among other things) as we walk, in our breath and emanations from pores in our skin, and Brundle isn't trapping any in his clothes as he isn't wearing any. Brundle has an invisible cloud of DNA floating around him in that teleportation chamber and as far as the machine is concerned their DNA has exactly the same status as that of the fly.