The plane shown taking off from the lake is a blue and white amphibian. The supposedly same plane shown in flight is red and white and not an amphibian. The plane taking off is a Grumman G-21 "Goose", which turns into an Aero Commander 520 in flight.
When the money in the armored car is finally seen, it appears to have been made on a black and white copier - the Treasury Seal and the serial numbers should be green.
In many gunfight scenes, the sounds of gunshots do not match up with muzzle flashes, etc., seen on the film - in addition to plain bad editing.
At the 1:29:00 mark Jack Palance says a line that is obviously dubbed by someone else, and the words don't match his lip movements.