Continuity
When Jonah Hill vomits on Seth Rogen and James Franco, they are completely covered in vomit. In the next shot their hair is dry and their t-shirts are only a bit wet.
When the possessed Jonah Hill violently vomits on James Franco and Seth Rogen, the penis statue can clearly be seen intact. This is the same statue that Emma Watson beheaded earlier in the film.
When Emma Watson robs the group by wielding the axe, she alternately holds the axe by the handle (like a baseball bat) and grasps the head of the axe.
Crew or equipment visible
When the beginning scene cuts to the hand-held camera following Seth Rogen, the camera which was filming Seth and Jay walk away from their meeting place can be seen.
Factual errors
When Jonah Hill is filming his confession after getting raped the camera shows it is powered from a wall outlet (A/C). However the power is out.