Why is it Tony changes every time he goes into the mirror? As noted below, the real reason is because Heath Ledger died prior to completing the movie, but there's an in-story justification as well: Tony's a liar and a con artist, so his appearance keeps changing to match the situation. Foreshadowed by the drunk in the beginning.
Valentina has sex with Tony in the Imaginarium — which is "facilitated" by Dr. Parnassus. He doesn't seem to always know what happens inside the Imaginarium, but it's still squicky. Basically, she has sex inside her father's head.
