In the radio station, Hector takes his gloves off twice.
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.
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.
At the end of the movie, Sam puts the pistol on the edge of the car's hood. A few seconds later, when the zombie guard attacks the little girl, the pistol has disappeared.
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 Regina is playing Tempest the next morning after the comet has come through, she is on level 7, but right after completing level 7, she is on level 11.
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.
When Hector is driving the red Buick convertible, the radio announcer states "It's 450 FM in the PM," but the Buick only has an AM radio.
When the comet is shown at the start it is pictured as if it is generating it's own source of light and it does not have a tail. (very rarely do comets not have tails.)
(at around 1h 05 mins) When the helicopter is taking off there is a window cleaning crew clearly working on the skyscraper in the background.
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.
The maze design used by the "think tank" has no way in or out to complete the sequence.
Just before Regina stops next to the empty Mercedes, a reflection in a building is seen with a person walking back and forth. Also, a car speeds by.
At 11:27 into the film, there is a person seen in the background exiting a building during the setup showing the empty city after the comet passed.
When Reggie first comes out at the front of the El Rey Theatre on the morning after, you can see the reflection of a moving car in the shop windows.
On the morning after when you see the scene after then traffic lights you see someone in the background walk into shot then turn round and walk out again (look for the white shirt).
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.
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.
Given the large number of people shown outside when the comet hits there should be significantly more clothing and residual dust left behind on the ground the following morning.