Continuity mistake: In the scene where Caveman and Zero found dirty water on the mountain, you see them splash around in it, but the next morning, in another scene, their suits are just dirty at certain spots. (01:26:50 - 01:29:00)
Revealing mistake: After Kate Barlow leaves the sheriff's office she runs down the road and past the store selling guns and powder. The words are backwards, showing the shot is flipped.
Factual error: When Stanley runs after Zero who is lost and finds him passed out, Zero offers Stanley "sploosh" which we deduce is rotten peaches from Sam's boat which they are taking shelter in. Had the peaches survived both the descent to the bottom of the lake after Sam was killed AND the effects of time, they would be extremely fermented and would be alcoholic. Stanley and especially Zero, would be drunk and would surely dehydrate to death or at least not be able to climb "God's Thumb" coherently.
Continuity mistake: When Stanley is calling for Zero, the flap on the back of his hat keeps changing when the angles change.
Continuity mistake: When Zero starts running away the warden we see from behind carrying her arms low. She says "don't shoot" then there is a shot of her front and she has her hands on her hips.
Continuity mistake: When Stanley first goes into the Warden's cabin there's a short shot of him looking up and analyzing the place with his hair a little messy and sticking up. Next shot his hair's neater.
Continuity mistake: In the scene when Armpit is doing his little break dance and lifts up his arms, Squid keeps appearing in and out of shots.
Chosen answer: It appears to be in fact a Coca-Cola bottle, it has been turned in an attempt to not show the logo.
LukeS