Several times you can hear the tires of the Sting Ray squealing from spinning while driving in the quarry. This sound is from tires spinning on pavement, not on dirt and rock in a quarry.
They drive the Sting Ray to the top of the quarry and suddenly there is a bare wheel on the rear to use for lowering the rope. They haven't had time to remove the tire from the wheel, they do not have the tools to remove the tire, there is no external trunk for carrying an extra bare wheel, and the spare tire carrier has a tire in it. Plus if they did remove it, they have no way to air the tire up once they reinstall the tire.
When Muddy and Arnie are sitting at the piano and Muddy places his hat on Arnie's head, there is no way that Muddy could be playing that specific passage of music on the piano with only one hand.
Tod tells Buz to put the Sting Ray in reverse and be easy on the brake to lower the rope, but the wheel is spinning slowly forward instead of reverse.