Corrected entry: M equips JB with a watch-mounted geiger counter to detect radioactivity. Then he hands him a radioactive homing device that he keeps on his person. Surely the homer would trigger the counter, but when he uses it the first time, the counter doesn't register.
Corrected entry: While climbing on the roof at Palmyra, Bond drops his Walther PPK. It slides a few feet down the roof and fires a bullet. Walther PPK pistols have a firing pin safety that does not allow the hammer to strike the firing pin unless the trigger is pulled all the way back. There is no way the gun could have fired.