When the four guys collapse on the floor, after eating the sprouts of evil, Richie still has the chalice in his hand. Yet when they wake up, the chalice is nowhere to be seen.
Just after the clock strikes midnight, Ritchie is wearing a different, much cleaner shirt. After he admonishes Eddie he has his original shirt back on.
During the fire fart scenes, you can see the hoses connected to the actors' rears.
Eddie is sucking up his hangover cure up his nose via straws, but the liquid is clearly not going up them.
When Eddie is sucking up his hangover cure through his nose, there is a tube visible underneath the glass sucking up the liquid.
The gang get nervous when they think the devil drinks virgin's blood. Hedgehog and Eddie have nothing to worry about as Hedgehog has a wife and daughter and Eddie admitted in previous episodes that he has had sex with a few girls.
Richie changes his tights three times, but makes no mention of changing his underwear.