Other mistake: When Anne and Peter are looking at the stars, Anne points to a star and Peter knows what star she's pointing to. It is impossible to point to a star and have someone else know exactly what star you're pointing to. Try it.
Continuity mistake: When Richard Hannay jumps from the Sheriff's window into a passing truck it is full of bales of hay. The next time we see him in the truck it is full of sheep and the bales of hay have vanished.