The Vikings (1958)

Factual error: The Vikings raided England in the 9th and 10th centuries. The first castles were not built until post 1066. The castle in the film has rounded towers, crenellations and machicolations, which would date it at approximately 1300. That would tend to suggest that these Vikings were 400 or 500 years old, or that they had access to a time machine.

Ragnar: Look how he glares at me... If he wasn't fathered by the black ram in the full of the moon my name is not Ragnar.

Trivia: The three Viking ships in the film were designed using blueprints for an actual Viking ship salvaged from the water and restored by a Viking museum in Norway. It turned out that the boats built for the film were too accurate, because the modern actors were taller than their historical counterparts. Every second oar hole had to be plugged so the modern men would have room to row with a full oar stroke. Otherwise, they would hit the backs of the oarsmen seated in front of them when pushing the oar handles forward to start each new stroke.