Deliberate mistake: In the sequence where Jack finds his friend, and then the cards he is holding counts down to the explosion. Jack runs out, and the house explodes throwing the cop car into the air. If you look close, you can see the piston that launches the cop car and then falls back down.
Continuity mistake: When Benedict pulls Leo's finger at the funeral to start the timer on the wristwatch, you can see that the timer was pre-set for ten minutes on the upper part of the display and the countdown is in the lower part of the display.There are two more shots of the countdown on the watch. First at 3:32 left when Jack knocks out the doctor and then at about 30 seconds left over the tar pits. Both of these shots show that a piece of silver tape has been applied to the upper half of the display, probably to cover a lower starting count so they wouldn't have to wait 10 minutes between shots.