During the final ten minutes, when we first see the whale surface with Captain Ahab bound to it tangled in the lines, he's hanging from a harpoon by his right hand, and the second harpoon is under his left armpit.
The second time the whale surfaces, the harpoons have been reversed, this time with Ahab hanging onto the first with his left hand and the second harpoon under his right armpit.
In the third shot, the positioning returns to that of the original shot.
The second time the whale surfaces, the harpoons have been reversed, this time with Ahab hanging onto the first with his left hand and the second harpoon under his right armpit.
In the third shot, the positioning returns to that of the original shot.
When Ahab is tightening the 3 straps on his new prosthetic leg, in the closeup he fastens the middle strap, then the bottom strap, but the top strap is completely undone. When it cuts to a wider shot, he is fastening the bottom strap again and the top strap is now fastened as well.
Fedallah throws two harpoons that stick into Moby Dick. In one shot, there is only one harpoon, though a second wound is visible. In subsequent shots, there are again two harpoons.
When Ahab harpoons Moby Dick, he has blood on his sleeves before throwing the first harpoon. The blood disappears in the next shot but is there again in subsequent shots. The presence and amount of blood on his sleeves continues to vary.
When Ahab pounds the gold coin into the mast, he uses a long nail. When the man pries it free, the nail is less than an inch long.
When Mr. Stubb calls for and is tossed a harpoon, the harpoon bends and wobbles, revealing it to be made of a soft, flexibly material, rather than wood and metal.