Not only in movies, in series too. Fake coffee. People takes hot coffee in a disposable cup, never burn their hand, can drink it like water or says damn it's hot but the cup is empty, they never dropped a drop, never choke, never spill it, etc. They can drink it and talk at the same time, run with it, etc.
I hate it.
It's a continuity thing, apparently. If the level in the cup keeps going up and down in a single scene, it's more distracting than a clearly empty mug.
This doesn't hold when the drink container is opaque! They can still put water or something in it so the actors aren't drinking from obviously empty cups.
I know this is a common complain, but they have tested with special cups that have weights and special compartments to have water. Audiences can't tell the difference. People complain that the cup is empty when it's filled with water, or are fooled by empty cups, so much as to not matter. Unless you can see the liquid in the shot it doesn't matter. The things like sipping or trying to move fast, are what gives away the state of the cup. Not the acting. And for those scenes there are other concerns like spilling, that are more trouble than they're worth.