In the movie The Grand Budapest Hotel, why is wine served in very small glass first to Mustafa?
It's probably (technically) a cordial glass. These are teeny glasses that are often wine glass shaped but are designed to only hold two ounces or so, which is the serving size of most cordials.
In the film, it's being used as a tasting glass, which is usually done in the full-sized glass already on the table or brought to the table when the wine is ordered.
Here's a video that outlines the tasting process: