The Concert is a 1956 ballet by Jerome Robbins. It's a spoof of the orchestral performance experience. The Pittsburgh Ballet Theatre summarizes it:
The setting is an all-Chopin recital where the attendees allow their decidedly imaginative minds to wander. When the resulting images are danced, human foibles and recognizable insecurities are revealed as Robbins brings each fantasy comically and vividly to life.
The ballet includes this piece titled "Mistake Waltz" in which some of the dancers are a bit out of sync. The above video shows a performance by the Pacific Northwest Ballet. Every error is completely intentional.
-via Nag on the Lake