I recently re-watched Lethal Weapon (1987) and I realized something I love a lot about movies... and that is to notice movie mistakes that you never noticed before.
Usually that happens the first time you watch a movie, but it can also happen even though it is the 15th time you are seeing a film.
While watching Lethal Weapon, in this scene, which is great by the way, Mel Gibson tries to prevent this suicidal guy from jumping off the ledge of the building. The specific scene starts at the 1:50 mark, and watch as Riggs at one point handcuffs the guy and makes him jump with him.
The revealing mistake is seen at 4:33 to 4:36. The handcuffs are not handcuffs, but a mear string attached around their wrists, that just snaps off.