While Raymond is vacuuming on Christmas morning, the backdoor in the kitchen goes from being open to closed and back though no one enters through that door during the scene.
Robert gives Ray a remote control airplane as a Christmas gift and tells him its a P51D that is a replica of the one flown by Chuck Yeager. However, Yeager's P51D had a red tail, a fuselage code of B6Y and was adorned with the words "Glamorous Glen III". The aircraft Robert bought has none of these markings.