Continuity mistake: Many times through out the film the red bag that contains all the money is not seen with the main group, even though they supposedly keep it with them at all times. The most noticeable example is when the two main characters first fly into Spain in the balloon and when the interior of the basket is visible the bag has simply vanished, but they have it again later.
Continuity mistake: Before Dr. Marvin removes the helmet from the dead alien, Maj. Huglin is holding his rifle in his right hand. In the next shot he's using his right hand to remove the helmet. Then in the shot after that he's not touching the helmet at all. (00:56:15)