When Ricky is having the car dragged up from the lake, it changes between day and night several times.
(At around 20:00) When the three men enter the study, John Jaffrey (Melvyn Douglas) is wearing black-framed glasses as seen from the rear, but from the front camera angle, his face is bare.
With David's naked plunge through the window, not only does the towel disappear but in the distant long shot of him falling from the building, there is no broken window.
When David plunges through the window, he has a large brown towel wrapped around him, but in the subsequent shots of him falling immediately after he is naked, and the towel is nowhere to be seen - if it had somehow come off it should be seen drifting down through the air.
In 1931, when young Sears makes a toast to the mystery of women, young John says "All women are a mystery to me." and sits down. When he's standing, his glass is in his left hand but immediately jumps to his right hand when he's shown sitting. And then a nearly-finished cigarette quickly appears in his left hand.
Robert Burr is credited as " Principal ". Since the school in the film is a college, his title in the credits should be " Dean ".
David's crashing against the window was filmed with Craig Wasson on a blue screen and a background where a cross iron bar is swung against the window on wires to break it in the same manner that a man which outstretched arms would. Craig's body was meant to block the cross iron but it does indeed become briefly visible under the right arm and side at the end of the shot.
When they are both shown shirtless, Don and David Wanderly (Craig Wasson) have the same birthmark on their upper right arm.
In the retelling of the 1931 events, Sears & Ricky describe Edward's impotence with Eva. However, Eva was silenced before she had a chance to reveal this information; information which Edward is not likely to have shared (at least, not truthfully.)
Don is back at Eva's mansion with a broken leg
on a freezing night. Yet Ricky decides it is more important
to have the car pulled from the lake first. Surely
this would be second priority to rescuing Don.