Continuity mistake: Lord Summerisle announces that it's time for the sacrifice to appease the gods of the earth. A horn is blown, and everyone turns towards it. In the shot from behind, everyone in front of Howie/Punch moved aside, but in the shot from the front, there's still a man with a flannel jacket and a badger mask.
Audio problem: On his way to check out the school, the Sarge witnesses a group of kids involved in the Maypole song. During the song, a kid with a mouth harp is strumming it every single time he's in frame, but that included large parts when the instrument is in fact not part of the diegetic song.
Continuity mistake: Back at the post office/sweets shop, Howie witnesses a bizarre bit of 'traditional medicine' involving a frog. The animal is held in close-up in a different way than in the first shot - the position of the last 3 fingers changes. Moreover, despite the spoken lines overlapping between shots giving the impression of continuity, the candy jar appears out of thin air, since the woman had just barely put the frog away in the other box.
Continuity mistake: Sergeant Howie is being quite critical about the food quality at the inn. Willow tells him that he can have "peaches and cream", and he replies "Aye, from a can I suppose." The beer fills his mug up to the top section of the handle. Brief cut to Britt Ekland, and in the next shot Howie's mug is half empty even if he didn't have time to drink - nor it is implied he moved at all, the position is the same.
Continuity mistake: Sergeant Howie cuts short the bawdy song at the pub banging an ashtray on the counter. You can then notice that in the wider shots the scarf at the neck of the owner of the pub is positioned differently compared to the closer views; a bit of it is untucked/tucked into the collar.