Continuity mistake: After Jack kills Halloran, there is blood on the blade of the axe, including the next couple of scenes chasing after Danny. However, when they get into the maze, the axe blade is bright and shiny with no traces of blood.
Deliberate mistake: Although Kubrick might've done this on purpose to show that the Overlook is unusual, as Jack is walking to the office to meet the manager, there is a left turn ahead, leaning to another hallway. When he goes into the manager's office, there's a window behind his desk that shows trees outside, but it shouldn't be there because that's where the hallway is.
Continuity mistake: As Jack talks and yells to Wendy at the writing spot, a chair appears behind him between shots.
Visible crew/equipment: At the beginning of the movie, Jack knocks on Ullman's office door and you can see Stanley Kubrick reflected in one of the square window panes behind Mr Ullman. Do not confuse Kubrick's reflection with Jack Nicholson's. (00:03:39)
Answer: Delbert Grady has always been at the hotel, just as Jack Torrance has...however, "Charles Grady" was one incarnation of the hotel's "caretaker", which Jack Torrance currently is. Delbert, evidenced by his appearance, occupation, and archaic racial views, has been with the hotel since its turn-of-the-century inception, just as Jack, in the photo at the end, has been. We don't know what "spirit-Jack's" function in the Overlook is...we only know that the present Jack (whom Delbert is talking to) embodies the "caretaker" who has always been there, just as Charles Grady did in his time. Delbert refers to his wife and two daughters, whom he did not murder...his "caretaker" version, Charles Grady, did that.