Within the 38th minute two dragon boat crew members pretend to be rowing with their hands empty. First a younger rower can be seen at the left hand side, in the background. The man is last but one rower at the right side of the boat and is moving back and forth as if he was rowing but actually he can be seen not holding the paddle. Then, in the next shot, when Ragnar walks along the boat toward Ivar, the last rower keeps rowing with empty hands.
Ragnar's boat has three or four rowing crew men depending on the shot.
In the final scene when Ragnar notices Ivar gets seasick shots picture three dragon boats. Ragnar's boat has three paddles extending from the inside. When the shot pictures the interior of the boat there are four crew men rowing.