Revealing mistake: In the scene were Charlton Heston has just said goodbye to Sophia Loren and is about to ride off with his followers (last scene just before the set intermission in the film), you can just make out a tiny little red automobile riding through the landscape in the background.
Revealing mistake: When in Boston, while walking through the park, Susan and her mother are obviously walking on a treadmill because the park background is moving way too fast for their walking speed.
Revealing mistake: In the taxi scene at the end of the movie, the steering wheel turns back and forth but the driver's hands are not moving.
Revealing mistake: The knives at the rumble bend EVERY time they move.
Revealing mistake: If you watch closely when the prisoner hits Jake with the shovel you can see the shovel bend as if it was rubber.
Revealing mistake: The Son of Hercules brings to the nearby village the old man that died on the beach. You can see the 'corpse' move his arm to assist Mark Forest as he dismounts him from the horse.