Other bloggers have made this point but it is important to re-iterate it.
A priest may hear confessions whilst Mass is being said, some priest suggest it is forbidden, Sacrametum Caritatis actually encourages it.
A priest may hear confessions during the Sacred Triduum, the celebration of additional Masses is forbidden, as is the distribution of Holy Communion, except as Viaticum. There is no ban on the celebration of the Sacrament of Penance. Though to be fair to priests Holy Saturday be pretty frantic getting ready for the Easter Vigil.