More Goofs!!
The many mistakes visible in "The Terror" are part of its charm, and I have no wish to belittle a film that has given me great enjoyment over the years.
Indeed, I was not aware of these goofs until the film became available on DVD which facilitates repeated viewing and clear freeze-framing.
1. In an early scene when Sandra Knight has shown Jack Nicholson the "clear water from the mountain" and he scoops up the water with his hands, a yellow hosepipe is clearly visible in the rock pool behind him. This presumeably provided the small waterfall we saw in the previous shot!
2. In the watery climax, when Boris (or his stand-in), Dick Miller and Sandra Knight are taking turns to duck/strangle each other. As she turns, Sandra has a clearly visible grin on her face.
Perhaps other fans might, in a spirit of fun, like to add to the list of goofs.