Running through the jungle mere inches ahead of those indian people, Indy - a man, let it be noted well into his forties - makes a clear break for his geataway plane in about 1.2 seconds. He is able to make a gap of a few inches into 50 meters between 2 camera shots!
a) Indy was NOT "well into his forties". The character was born in 1899, making him 37 at the time the movie took place.
b) The natives were never "a few inches" from him. Exaggeration like this really demonstrates that you know it's not much of a slip (if at all) but are trying to make it seem like it's a big deal.
c) The man is RUNNING FOR HIS LIFE. The pursuers tactic is run, stop to fire a bow/blowgun, then take up chase again. This is blatantly SHOWN in the scene more than once. So OF COURSE he's going to open up a gap.