Continuity mistake: After President Whitmore comments to General Grey that the pilots look young and nervous, when Major Mitchell speaks into the mic and asks for all flight crews to report to their designated areas, the President climbs up onto the truck behind Mitchell. Next shot though, he is only just now walking toward the truck and then climbs up. (01:55:10)
Continuity mistake: In the diner, when the alien destroyer is about to pass overhead, things begin to shake as Russell sits at the counter and the three guys are at the table. In the close-up of the table, the salt and pepper shakers appear near the coffee cup, the Diet Coke disappears and everything changes position - having nothing to due with the table shaking.
Continuity mistake: As Smith leaves Jasmin to go to El Tore his uniform jacket's epaulettes are untucked then tucked and finally untucked again.
Audio problem: The same female scream can be heard three times during the first attack by the aliens. It is first heard in the scene when Jeff Goldblum is riding his bike to his father's house. The second time it is heard right as Jeff gets to his father's door. The third time is in Los Angeles when the people are running away. It's a very distinct scream.