When Scooby sees the Skeleton Men through the periscope, the view is following the Skeleton Men, but the periscope is not moving.
When Fred and the girls are trapped in the dry dock, which is being flooded with them inside, Daphne says "Jeepers! We're doomed!" just before Shaggy and Scooby rescue them. When she says "doomed", her mouth is closed as she says it and then opens after she's finished saying "doomed."