When Murray throws the silver dollar into the muddy puddle, it immediately sinks into the cloudy water. But when he get Jammie to come over to fish it out, when the camera does a close up on the silver dollar, it is no longer hidden in the muddy water, but on and above it. A platform had obviously been made (of mud?) in the mud to make the silver dollar protrude above the water.
When Jamie is tricked into operating the machinery, he and his stunt double wear differently colored pants.