Carlton's white headband appears and disappears between shots before the family goes for a workout, even though he is later seen wearing it at the gym.
When Nicky picks up the modeling glue to hand to Will, it cuts to Will making a hand gesture, indicating he hasn't taken it yet. But when it then cuts back to Nicky, the glue has disappeared.
When Will gets thrown around the gym in his dream, it is obviously a dummy without facial features and not Will Smith.
When Will and Carlton arrive to the gym, the woman on the treadmill is walking, however, the treadmill is not moving. This is shown multiple times.
Will and Helena are sparring but aren't wearing protective headgear and mouthpieces.