When the initial scene in the projection booth begins, we see a steel shipping reel running at the top of the projector. In all other shots after that one (presumably within the same 20-minute running time of a 2000' 35mm film reel) the reel changes from the steel shipping reel to a cast aluminum house reel.
When Reggie first returns home the morning after the comet, the entryway carpet is clean and clear, yet after finding Sam upstairs and then dragging her toward the front door, there is a pet leash and a small spot of red dust in the middle of the carpet at the bottom of the stairs.
In the department store, they start with a double-speaker Toshiba "boom-box". When Sam is apprehended by the store's new "owner", he directs his henchman to "turn off the music" (sic). The boom-box is now a single-speaker, generic tape player/radio when he shoots it.
Near the buffet table at the party scene in front of Samatha's and Regi's house, there are hundreds of people in the whole area watching the comet. But after the comet leaves, there are perhaps not even fifteen pieces of clothing remaining from all the disintegrated people there.
On the morning after the comet when Regina and her boyfriend wake up in the projection booth, Regina is shown alone in the sleeping bag. It appears as though she is topless as there are no signs of her wearing a shirt or having anything over her shoulders. After a quick cut away to her boyfriend, Regina, still in the sleeping bag, can be seen wearing a "tank top" type of shirt as the shoulder straps are now visible. There was not enough time for her to put on a shirt nor did she leave the sleeping bag.
In the beginning of the movie, Regina is playing a Cabaret style Tempest game in the theater lobby. The next morning the game is a full size upright cabinet version. It's supposed to be the same game because of the high score mistake already noted.
At the beginning of the movie there are thousands of people in front of the movie theater where Regi works watching the comet. But after the comet leaves there are only a few pieces of clothing remaining from all the disintegrated people.
When Regina first enters her house, the cereal box and milk are on the kitchen counter before Regina finds Samantha upstairs. After Regina finds Samantha upstairs and they enter the kitchen, the cereal box and milk are not there. Samantha gathers the cereal and milk and places them on the kitchen counter.
As Regina drives down Hope St. and turns right at a street, you can see someone in dark clothing reflected in the shiny stone wall walk in front of the light source to the far right, then turn around and walk back in front of the light source again.
When Regina types in "REG" as high score position #6 on the video game (Tempest), it would have dropped "DMK" to position #7, not eliminate it entirely. Also, the top high score visible during her previous game play is 296844 points with the associated initials of "D R" (not "REG", whose top high score is implied). Regina's score during game play is upwards of 80000 points, yet when she enters her high score in third place the second, third, and fourth high scores are 45XXX, 37XXX, and 35XXX points respectively. However, the following shot of "DMK" being in sixth place shows the adjacent high scores in the 15XXX range. Lastly, the levels shown ("heart" level, "line" level, etc...) do not coincide with actual gameplay.
When the lab generator shuts off the victim on support dies due to the respirator stopping and he shown dying via a shot of a heart monitor screen flat lining despite the fact that the power failure would have rendered the monitor inoperative as well.
If all the people (or life in general) would be destroyed in a couple of seconds the streets of Los Angeles would be full of crashed cars. Actually, the streets, highways and parking lots in the movie are completely empty.
Near the beginning of the film when Reggie flees downtown LA on her boyfriend's motorcycle, she comes to a stop beside a brown Mercedes 300D. If the driver had disintegrated at the traffic light, his foot would have come off the break and the car would start rolling until it was stopped by hitting something.
When inside the radio station, automated reel-to-reel tape decks are activated to simulate a live radio DJ cuing tracks. Neither tape machine shows activity in its VU-level meters, revealing that the machines filmed for the movie were loaded with blank tape.