Revealing mistake: When the swimmers are being attacked, some of them are not even panicking.
Piranha 3D (2010)
1 revealing mistake - chronological order
Continuity mistake: When Jake goes into the water with the tow rope around his waist, the rope is going over the top and through the railing of the boat. When he gets pulled away with the girl, the rope is seen down in the water.
Novak: There are thousands of them and they are pissed!
Trivia: In the opening scene with Richard Dreyfuss fishing on the lake he is singing to himself "show me the way to go home". This is a nod to the movie Jaws because it is the song that he sang along with the rest of the crew as they waited for the tagged shark to be re-sighted. (00:01:00)