David Franks' leg is bitten off during the first scene, but it reappears in the next scene.
In a previous scene, when Franks initially climbs into the underground cavern from the underwater tunnel, he sheds his tank and regulator.
At minute 35:00 he jumps back into the water without his tan and regulator and is then shown a moment later wearing both the tank and regulator.
At one point Laura is in handcuffs. In another scene, she is tied up with rope.
When David Franks pull the briefcase outside his dad's apartment window into the room, it dries instantly.
The divers all speak very clearly underwater, despite the breathing apparatus in their mouths.
When David Franks goes to his father's flat to investigate his death and finds a briefcase, he says the 8th crusade was sponsored by the Louis XIV. The 8th crusade started in 1270; Louis the XIV was born in 1638.
The name of the Italian family engraved on the plaque is spelled "Medicci". It should be spelled "Medici."
The mafia goons arrive by boat to kidnap Vanessa. As the boat pulls up to the dock, only the top half is visible, and its clearly on wheels.
When the bandits chase David from the hotel, the same extras and props are recycled numerous times, even though they are apparently not supposed to be running back and forth through the same places or past the same people.
Several scenes during the final fight scene are played in reverse.
At minute 30, Franks finds a hole in the roof of the underwater tunnel which is shown by the light above. After climbing through the hole, the area is completely dark, with no light available to show through into the underwater tunnel.
At minute 50:26 while the shark is attacking, one scene shows a wide open blue ocean skyline, the next scene is back a Venetian canal.
David is attacked by the shark that kills everyone else it chomps, leaving him only weak from losing blood and unconscious for two days. Yet he awakens and immediately leaves the hospital at full strength with no visible injury or impairment. Deadpool would have a hard time matching that rate of recovery.