When Bill is grabbed from the bridge, most shots show him wearing what appear to be ear protectors (from all the shooting he had been doing?). There's at least one shot where the protectors are missing, only to reappear a moment later.
At one point Jimmy says the bomb shelter is from World War 2.
Later he says it was built to withstand a nuclear attack.
The first nuclear bombs were only just being developed by the US during World War 2; they would not have been building shelters intended to withstand nuclear strikes from other countries who did not yet even know such weapons were possible.
When Mohawk was firing his mini-gun, the recoil should have sent him flying, yet he was able to fire without even a wobble.
After blowing up the bomb shelter, Burt says 3 dead graboids... There was no way of knowing how many graboids were there, whether there were 3 or not, and how many have died.
When told Travis was busted carrying "magic mushrooms" across the Mexican border, Burt refers to them as "peyote." Peyote comes from cacti, not mushrooms.