Continuity mistake: In the first successful teleportation of the baboon, there is one scene where Brundle's hands move from being straight to folded in just one shot.
Continuity mistake: When Geena Davis gets kidnapped by the Brundlefly from the hospital, he gets into her hospital room by crashing through a plate glass window. When he leaves through said window we see that a portion of the left side has broken in half and is severely cracked. When John Getz's character attempts to stop them he smashes his hand through the same window section that's somehow become immaculately whole again.
Continuity mistake: When we see the first close-up of Stathis' dissolving hand, we see the fly vomit on his sleeve. In the next two shots of his hand, the vomit is gone. Then, when Stathis has fallen on he ground staring at the dissolved mess that was once is hand, the vomit is back on the sleeve.
Continuity mistake: When Seth cuts the steak in two pieces, one half is larger than the other. He then puts the larger half on the white and brown plate to teleport it. After cooking both pieces, he puts that larger half on the white plate. Seth then gives the smaller half on the white and brown plate to Veronica and tells her it's the piece that was teleported. Furthermore, when Seth cuts a very small piece from the larger half to give to Veronica, the next shot shows two remaining pieces on the white plate although only one piece should remain.
Continuity mistake: After Stathis Borans gets his left hand melted, in a few shots later we can see his whole hand back again.
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.
We don't know enough about how the machine works to determine how it might differentiate different DNA types. Unexplained science means it's somehow able to do it. Willing suspension of disbelief for the win.