The movie is wrong. - I did not even know it gave a room number.
The only rooms to have G numbers were a block of rooms aft on G-deck that could be used by either 2nd or 3rd Class passengers. - Not both at the same time. - Room Numbers G-1 to G-41 [no G-13].
If you go to the deck plans on this web-site you will see them in the section labelled 2nd Class and located around the No 5 Hatch. If the rooms were 2nd Class then the stairs in the centre were used. If 3rd Class then the ones on the port-side.
The numbering system for 3rd Class rooms involved sections. Single men were generally berthed forward.
Room 60 was in section "E" and was the room immediately outboard of the forward set of stairs on the port side of the upper level of the Squash Court on F-deck.