Factual error: In the scene where Daniel is flying the B-25 (Mitchell) to see Helen, you can see the propellers are turning much slower than needed for a cruising flight. Also, the sound of the engines is too low and keeps changing even though Nat and him are talking.
Factual error: In the scene where Daniel is taking off with the "borrowed" B-25 (Mitchell), they have two shots switched. It shows him taking off (a beautiful shot), and the very next shot it shows him adding power through the throttles. This should be reversed.
Chosen answer: Harry Findlay only discovered the ageing would irreversible after Daniel had been frozen; don't forget this was the first time he'd tried it on a human. Plus he only ever intended to freeze Daniel for a year, so this may not have been the main focus of the experiment anyway.