Continuity mistake: When the crew hauls the female orca aboard the boat, the harpoon line is wrapped around her entire body several times. When they cut the rope and drop her into the water, the line is wrapped only around her tail. When the male orca is pushing her at sea, the rope is again wrapped around her entire body.
Factual error: Near the beginning, when the crew is chasing the great white shark and trying to avoid hitting the raft, Captain Nolan yells to the pilot "Hard to port." The pilot turns the wheel to the right, which is starboard.
Continuity mistake: At the end when Orca leaps from the water to land on the ice causing Harris to slide down, the ice isn't there then all of a sudden it appears when Orca lands on it.
Continuity mistake: Sometimes the orca is seen with the nick in his dorsal fin, and sometimes there is no nick. The is most obvious when he sinks the boats in the harbor. When he heads into the harbor, the nick is visible, when he leaves the harbor, there is no nick in the fin.
Revealing mistake: In the beginning of the movie when Orca is about to hit the great white shark out of the water the stick that holds the "head" of the great white is visible as it swims by.
Revealing mistake: Obvious prop orca when it's up on Captain Nolan's boat.