As reported some viewers in Tucson, Arizona who were watching the game on Comcast cable's SD feed got exposed to a porn clip during Super Bowl. Comcast has now issued an official statement regarding the incident.
Comcast says that the initial investigation suggests this was an isolated malicious act. There is still no information on how the porn clip got fed into the Comcast SD stream, but an investigation is underway.

The company is of course deeply sorry as the Super Bowl is a family viewing event. Comcast is handing out a $10 credit to any Comcast video customer in Tucson who was impacted. The Super Bowl Porn glitch made it of course already onto Youtube.
More details on the KVOA site. Via WSJ.