There’s only one hand on my Fez Clock

If you've already collected three anti-cubes from the Clock Room, then the clock itself is correctly displaying only one hand - each one of the cubes you collect will cause its corresponding hand to briefly flash and disappear.

Check this YT video at (0:23) for a demonstration of this effect:

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If you need a reference on which clock hand you still have active, this old Arqade question has a list of each hand and their estimated time cycle.