Continuity mistake: During the car chase between Fitch and Diaz, Diaz's truck changes from a Suburban, to an Explorer, to an XL-7.
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.
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.
