Wot, do blue whales have wheels?!
I cannot see any clear sign of a propeller and nothing apparent on the wheels, but photo 2 shows quite a bit of splash coming from the port main wheel, and photo three appears to show a paddle blade or vane (at 11 0'clock) so perhaps these were bolted on for aquatic antics. It makes sense for a small vehicle to use a single power train for land and water, no extra components, weight or complication. However, it sits low in the water, with the water line at wheel centre, too high for efficiency; a paddle should be only 1/4 of its diameter into the water.