Danny's hand, through which Tony speaks, can only be seen in the reflection of the mirror, on this side of the mirror his hand is obscured by his head - just as Stuart Ullman blocks the eagle in the windowsill with his head. Danny has named his mirror persona to keep himself intact - like Jack he accepts the visions, but unlike him he processes what is happening differently.

DANNY Tony, why don't you want to go to the hotel?
TONY I don't know.
DANNY You do too know, now come on tell me.
TONY I don't want to.