When Q first uses his flamethrower, when he is flaming the wasps near the van, it later shows the decals burned. Later on in the movie, the decals on the van are no longer burned.
Kent, Dr. Brown, Q and Rafe destroy the swarm by luring them into a garage filled with gas from propane tanks stored for the cook-off. However, these tanks have safety valves that do not allow gas to escape unless the tank is attached to a grill.
When Q attempts to kill the swarm with the flamethrower at the fair, the heat and flames do not melt or destroy the plastic flags and bunting (revealing the flames to be an obvious post-production special effect).
The story is set in an Indiana town but the police are wearing shoulder patches from the New York City Police and Badges from the Royal Canadian Police with the British Crowm visible on top of the badge.
Canadian speed limit sign visible when Kent and Cristina get Q and Rafe to pull over.
Kent and Cristina walk past a shop window that has a Canadian flag and English and French writing.
In one scene where Q and Kent are talking outside, Q has a set of goggles on his forehead and the boom can be seen reflected in them.