When Jamal is back at the lake, debating whether it's his fight or not, the medallion is tucked inside his shirt. When he turns to face the camera it's suddenly outside his shirt, and when he turns around again it's back inside.
When Jamal is lying down on his bed after being knocked out, Victoria pulls out his chain to inspect it. When he is stirred by her touch and sits up, the chain is no longer hanging out but is neatly tucked back into his shirt.
When Jamal is introduced by the dwarf before he talks about "Jamal in the Box" he has his pocket on his shirt to cover the logo underneath, but when he asks if anyone has had a froth-a-chino it is gone to reveal the logo and then the very next shot it is back on there again
When Jamal is in front of the lake ready to go back "home" (before he changes his mind), in the first shot his medallion is clearly tucked in his shirt, in the next shot, when he turns back it's out, and in the very next shot it's tucked back in.
The executioner tries to cut a melon with an axe two times before turning the axe blade sideways, and smashing the melon. The force of a blow from the edge of an axe would be greater than from the flat, so if he can't cut the melon, he should not be able to break it with the flat of the axe either.