there is however a bug where if the two available slots are positioned so one is above the other, the domino will drop into the top slot despite aiming for the lower.
you can replace relics, just hit the X above them. Costs 10 gems, but it's a great option. In addition, if you scroll down it should open a second menu which gives you the option to forfeit your turn to do any of the basic movements; forward, backward, and turn around