Murdoch throws two coins onto a stone table to set off any potential traps. The first coin hits, but rolls completely off the pedestal top, landing on the ground. Murdoch throws another coin just to be safe. This coin lands on the very far edge of the pedestal top. As Dr Iris Bajjai get closer to the object on the pedestal top you can clearly see that the second coin Murdoch tossed is still in the place it landed. However when Murdoch and Dr Bajjai go to move the top off, there are now two coins on the top, nowhere near where the second coin stopped, and it's joined by the other one that fell on the floor.
Both Murdoch and George say that the Temple of Death is "full of booby traps." But when they say that, they have only seen the one trap, the one that killed Bashar Kaba. It is only later that they discover the other traps.