While Claire is bandaging Daniel's cut hand, her blouse is unbuttoned, buttoned, and unbuttoned several times.
The first time Daniel arrives at Nat's house and chases Nat and Felix into the tree house, Nat hits Daniel's hand with a hammer and Daniel clearly drops Nat's jacket. In the reverse shot, he's still holding the jacket. It disappears and reappears in his hands a couple times.
While Daniel is about to make dinner, Nat's hands are alternately folded/resting on the table between shots.
At the start of the movie, around 00:04:35, when Daniel crash lands the B-25 prototype, the first time it hits the ground the forward upper part of the canopy over the nose of the plane crumples. In all subsequent shots of this area there is no damage.
When Daniel attempts to enter Alexander Field, the gate guard denies him access. In one shot, from behind the guard, he has his left arm extended to physically impede Daniel from entering as he tells him that he cannot allow him to enter. In the next shot, from a reverse angle behind Daniel, the guard now has his right arm extended to block Daniel's progress.
At time index: 58:18 you can see the LT. COL driving into base and on his windshield is a D.O.D. Parking sticker which is yellow. The sticker for him should be Blue as he is an Officer. Green and Yellow stickers are for civilians.
Set in 1939, Daniel flies a B-25 Mitchell, which did not have its first flight until August 19,1940.
At one point, Daniel drives past a sign reading to "Los Alamitos Air Base" which appears to be among some dry hills, while the real Los Alamitos Air Station is in the middle of the suburbs, where there are no hills.
Helen's house was locked when Daniel and Nat landed. Although it is very isolated and Helen just went out for some flowers. She should not be afraid of burglars.
After the crash the doctor uses his stethoscope on Daniel, but it's not in his ears.