Moving while leaving boat leaves you 'mouse paralysed'.

If you leave a boat while moving, when you exit you will no longer be able to use the mouse buttons as intended. Your hands disappear and cannot be seen. The only thing you can do (using the mouse buttons) is break blocks: you cannot place blocks, attack enemies or any entities like boats. The glitch only works some of the time, so it takes a few tries to replicate it. It is easily fixed by leaving and reloading the world.