Continuity mistake: While Sam is talking to Trudy in the bank about the burned church, the name tag on the door in the background when the camera is focused on Trudy is there, then it isn't, then it reappears again throughout the scene. (00:35:30 - 00:36:00)
Revealing mistake: When the soldier is tempering, you can see sparks fly before the hammer hits the metal.
Factual error: Corey and Randy are riding his bike down the street, and talking about Sam's demise. As they pass an alley, there is a Mitsubishi Eclipse which is newer than 1995, the year the events take place. It appears from the rear end to be about 4 years or more newer than 1995.
Factual error: The film takes place over a few days at the beginning of July 1995. On the movie marquee in Conejo Springs, the movies playing are 12 Monkeys and Strange Days. Strange Days was not released until October 1995.
Factual error: Almost all the semi-tractor trailers on the Interstate passing by are from the 2000s, not 1995, the timeline of the movie.
Chosen answer: Nope. It was just a reaction to the meteorite. It could have been an alien bacteria causing it, or it could have been an allergic reaction to one or more materials in the meteorite itself.
Phixius