Bytes 12 to 15 of the saved legs record at plyr_spr_1_scratchpad. +$0C holds movement state bits. exit_screen sets its top nibble to 3 before saving, and the legs' handler counts it down by one a frame: while it is non-zero the turn and jump controls are ignored, the legs keep walking, and the room-boundary check at adj_dX_for_out_of_bounds is skipped -- which is presumably what walks him in through the doorway. main clears this byte for each new game.