The Blue Lagoon (1980) - 2 major mistakes

Continuity: There is a scene in which it is raining quite heavily and Em and Richard are inside the hutch. Richard is playing Pop Goes The Weasel over and over which annoys Em. She stabs him in the foot and he chases her outside. In this scene she is wearing a strapless dress but when he catches her and pins her down on the sand she is wearing a lacey jacket (she didn't have time to change) and there are no clouds or rain. The sand doesn't seem to be very wet either, despite the fact that it was raining heavily a few minutes ago.

Other: This mistake happened right after Richard evicted Emmeline from their hut. We see Emmeline under some rocks and it is raining. See has a makeshift wall made of palm leaves. The rain is coming down to the left, but the wall comes down the opposite way to the right, against the wind and the rain. The director mentioned on the commentary they used ropes to do this.