[Big O]

Here are some rules from ROberts Rules

The following circumstances cause a misdeal, provided attention is called to the error before two players have acted on their hands. (If two players have acted in turn, the deal must be played to conclusion, as explained in rule #2): a) The first or second card of the hand has been dealt faceup or exposed through dealer error. b) Two or more cards have been exposed by the dealer. c) Two or more boxed cards improperly faced cards) are found. d) Two or more extra cards have been dealt in the starting hands of a game. e) An incorrect number of cards has been dealt to a player, except the top card may be dealt if it goes to the player in proper sequence. f) Any card has been dealt out of the proper sequence (except an exposed card may be replaced by the burncard). g) The button was out of position. h) The first card was dealt to the wrong position. i) Cards have been dealt to an empty seat or a player not entitled to a hand. j) A player has been dealt out who is entitled to a hand. This player must be present at the table or have posted a blind or ante.
Action is considered to occur in stud games when two players after the forced bet have acted on their hands. In button games, action is considered to occur when two players after the blinds have acted on their hands. Once action occurs, a misdeal can no longer be declared. The hand will be played to conclusion and no money will be returned to any player whose hand is fouled.

Procedure for an exposed card varies with the poker form, and is given in the section for each game. A card that is flashed by a dealer is treated as an exposed card. A card that is flashed by a player will play. To obtain a ruling on whether a card was exposed and should be replaced, a player should announce that the card was flashed or exposed before looking at it. A downcard dealt off the table is an exposed card.