Note that the 2c isn't dealt as part of the live hand - it's the players rabbit hunting after the Cannon folded on the flop, so the deck stub has been mixed with the mucked cards (including the Cannon's cards). The dealer is probably just guessing where the "correct" cards were supposed to be.
You could call it a dealer mistake, I guess, but we're talking about rabbit hunting here so she probably wasn't paying a great deal of attention. It's not like it affected the hand or anything.
As for something like this happening as part of a live hand, it's certainly possible - misprints happen in decks from time to time, which is why you should always check a deck before using it. In a casino, any time a new deck is brought into play the dealer will check it (and often they'll have a supervisor confirm that check too) to ensure it's correct, so issues like this one should be very rare in a casino game. If it were to happen though, the following rules apply (from Robert's Rules of Poker (http://www.homepokertourney.com/roberts-rules-of-poker.htm#IRREGULARITIES)):
4. If two cards of the same rank and suit are found, all action is void, and all chips in the pot are returned to the players who wagered them (subject to next rule).
5. A player who knows the deck is defective has an obligation to point this out. If such a player instead tries to win a pot by taking aggressive action (trying for a freeroll), the player may lose the right to a refund, and the chips may be required to stay in the pot for the next deal.
And as far as seeing something like this on TV, I think I can remember one similar incident (can't remember what show it was on) but it turned out to be an editing error - they either showed hole cards from a previous hand, or misreported the contents of a mucked hand in the on-screen graphics (said one card was 7c when it was actually 7s or something).