The injuries to both players were sustained in an Irish squad training session at Naas.
Mike Mullins has fractured his jaw following a collision and faces an operation in Limerick on Thursday. He will be out of action for five to six weeks and that rules out any possible return to the Irish team for the duration of the Six Nations Championship.
However, Munster are confident Mullins will be back in the red shirt for the quarter-final of the Heineken Cup against Stade Francais on April 10th.
David Wallace pulled up in training after he aggravated a knee injury that he sustained in the match against Bourgoin in the last of the Heineken Cup pool games. The full extent of Wallace's injury will be known over the coming days.