Continuity mistake: During the car chase between Fitch and Diaz, Diaz's truck changes from a Suburban, to an Explorer, to an XL-7.
Revealing mistake: The guns that the soldiers use to kill piranhas with are actually Nerf Longshots that you can buy at the toy store.
Continuity mistake: Throughout the movie they show scenes of the military flying UH-60 Blackhawk helicopters. During these flights they sometimes cut to scenes only showing the prop-shaft of a helicopter. However the prop-shaft is that of another helicopter (possibly a Bell Jetranger, a heli widely used for filming).
Continuity mistake: During the movie a US destroyer is radioed to use its guns and missiles to shoot at the piranhas. The first shot shows not a destroyer, but an LPD or a transport ship. Then they switch to a destroyer or small cruiser in a later shot. After that shot, the destroyer turns into a 58.000 ton Iowa class battle cruiser. This can be seen by the two forward turrets that house three 16 inch guns. Problem is that this class was decommissioned before the movie takes place.
Factual error: After they order the Ohio class submarine to nuke at the piranhas, they show a scene were the submarine launches a torpedo that explodes with a large flash like a nuclear explosion. In a scene before that, they say it is armed with a 20 kiloton nuclear device. However, the US Navy had only one nuclear tipped type of torpedo, the Mk 45. They were decommissioned in 1976. Also, it used an 11 kiloton warhead.
Continuity mistake: Before the piranhas attack Florida, officials order an Ohio class submarine to strike at the fish using a nuclear torpedo. The first shot of the sub shows that Ohio class submarine. However, when the piranhas attack the submarine, the Ohio class turns into what appears to be a Soviet-built Alfa or Akula class submarine.
Factual error: The movie takes place in Venezuela. Throughout the movie the Venezuelan army flies US-made UH-60 Blackhawk helicopters. However the Venezuelan army does not fly these, nor can they purchase them, since Venezuela is boycotted by the US.
