(at around 8 mins) When Charlie relates his Critter history to Annie and Josh, he says it all started in 1984. (at around 32 mins) Yet Mr. Menges' tabloid newspapers (and the release date of the first film) would indicate the first attack was in 1986.
(at around 1h 4 mins) Notice when Annie is shielding herself with the sign that reads "Outa Order" from the Critters shooting their spines at her. Charlie comes in and blows one of the Critters away causing its green goo blood to spray all over the sign. In the next scene Annie is shown holding the sign but now it's totally clean.
(at around 7 mins) Josh bends down to retrieve the Frisbee. In the shot from ground level, the Frisbee is resting on top of the branches, but in the next shot it's underneath them.
(at around 2 mins) The camper van has a flat and there's a shot of the shredded tire. When they park up in the rest area, the tire is back in one piece on the rim, with no damage visible.
(at around 57 mins) When a Critter's stomach inflates before passing gas, beans suddenly appear on its fur and then disappear.
(at around 2 mins) When the camper has a flat tire, you can briefly see flames, indicating there was a charge to flatten the tire. A tire bursting doesn't cause flames.
(at around 39 mins) When Annie's dad is hit for the first time by a spike of the critter, there is a spot on his hand where the spike is about to hit.