When Abruzzi's pilot becomes spooked as they hear the sirens come closer, he says "We've gotta go." The next shot shows the approaching police cars, and if you look closely, you can see the inmates run off to the right, even though they have not arrived there yet.
During "1.21 Go", Sucre moves the toilet back into position against the wall, but near the beginning of "1.22 Flight" Warden Pope sees the toilet out of the position and the hole into the pipe system. However, that's because one the guards had already moved it out of the way after their escape route had been found.
When the van gets stuck in the mud Lincoln asks, "how far is the airstrip?". Michael responds, "on foot, maybe two miles." The distance does not change depending on the mode of transportation.