"Any theory of hallucination breaks down on the fact (and if it is invention [rather than fact], it is the oddest invention that ever entered the mind of man) that on three separate occasions this hallucination was not immediately recognized as Jesus (Lk 24:13-31; Jn 20:15; 21:4). Even granting that God sent a holy hallucination to teach truths already widely believed without it, and far more easily taught by other methods, and certain to be completely obscured by this, might we not at least hope that he would get the face of the hallucination right? Is he who made all faces such a bungler that he cannot even work up a recognizable likeness of the Man who was himself?" (Miracles, chapter 16)
A more detailed response to hallucination theory can be found here.