Trident Duplication

Throwing a trident (without the riptide enchantment) and dropping it on the ground at the same time, if timed right, will throw the trident and drop it at the same time. Picking up the trident dropped on the ground and the trident that was thrown will result in picking up two tridents even though there was only one trident originally.

This has been replicated by a few other people and has been found to work both in singleplayer and in a Realm. I haven't tested this in any other editions of Minecraft, though I would guess it might happen on other editions.