Madonna took to the stage for her halftime show during Super bowl XLVI.
Beside her were Roman soldiers, the duo of LMFAO, Nicki Minaj, and Cee Lo Green.
The NFL and NBC issued apologies late Sunday.
NBC said: "The NFL hired the talent and produced the halftime show. Our system was late to obscure the inappropriate gesture and we apologize to our viewers."
An NBC spokesman explained that a system in place during the telecast attempted to blur the image but was late by two-third of a second, or 20 frames. He could not identify how many seconds of delay were in place during the broadcast.
The NFL issued a statement, saying: "There was a failure in NBC's delay system. The obscene gesture in the performance was completely inappropriate, very disappointing, and we apologize to our fans".