Other mistake: When the Vikings are chasing the main characters in the boats, the Vikings' ship isn't moving although they are still rowing.
The Island at the Top of the World (1974)
1 other mistake
Directed by: Robert Stevenson
Starring: Mako, David Hartman, Donald Sinden, Jacques Marin
Visible crew/equipment: There's a scene where the airship Hyperion is flying low among the icebergs and the Captain is bragging about his piloting prowess. In one shot the ship emerges from behind a pillar of ice, and the shadow of a large piece of overhead rigging falls over the top of the miniature berg.