The sniper can travels from the departure level of LAX to the arrival level in about 20 seconds. That would hardly be possible in 20 minutes at most days and times at LAX.
Only a very short person can stand up straight in the baggage hold of a 737 and then only in the middle. Average sized men could not possibly fight standing up.
Parachuting out of an airliner at cruise altitude is impossible. Due to the pressure differential on the doors, the opening lever would break long before the door could open (assuming one had super-human strength).
At the beginning of the movie, the tree-pruner tosses a key fob and says "..in back of blue BMW." The key fob shown does not match a BMW, and looks more like a Chrysler/Dodge key fob.
The end scene in the cargo compartment of the 737 is incorrect. Both actors can stand up straight and still have head clearance. The height of this compartment is much smaller. You can definitely not stand here.
A person wearing a yarmulke like Herschel would not crave a non-kosher item like Ho Hos.
Inside aircraft is depicted too large.
There are no security cameras in public bathrooms, as that is illegal. Ethan could have simply gone into one of the employee bathrooms to call the police, send the text on his watch, or write the note, and the bad guys would have no way of knowing.