There's no reason why notyou wouldn't be able to
Unless an illusion says that it is justonly appears in a target's headmind, then it actually takes a visible form for all to see, so there is no reason why it wouldn't show up in a mirror or any other reflective surface.
And even if it does appear just in the target'target's head, it is still projecting it'sits presence into the person's head, so there is no reason for it to not also appear in the mirror as far as the target is concerned.