Both Rita and Diane pick up a name at Winkie's. Rita sees the name tag "Diane" and thinks perhaps that her real name is Diane. Diane sees the name "Betty", which is the name she is giving herself in the dream sequence, because Betty represents the innocent part of her life, working at Winkie's, a place that is not associated with the sins of Hollywood. »name tags
The waitress’ name at the Winkie's is a connection between the pink world and the reality world. First of all, Diane can’t accept that Camilla put an end to their love relationship. Indeed, Diane is desperately in love with Camilla and wants her to pay attention to her in her imaginary pleasant world. The mere pronunciation of the name "Diane" enables Rita to recover her memory. Also, the Winkie's restaurant was chosen for the deal with the killer in the reality world. By giving her real name to the waitress in the dreamworld, Diane conceals the fact that she has paid a killer to slay Camilla. - (Cécile Lagrange & Doriane Mouret)
In the end though, the real Diane hated herself for the depths to which she had sunk. It came to the point that she took the identity of the waitress, Betty – the irony does not escape me here... most young women who go seeking fame and fortune in Hollywood end up failing miserably and working in a diner. Diane, who managed some modicum of success but owes Camilla for it, would rather be the waitress with a clear conscious and a fresh slate. - (Bob)
Has Diane been working as a waitress to get by (since she was a struggling actress)? Remember the waitress at Winkie's in the dream was named Diane and the coffee mug at home resembled the ones in the diner. But then, it would seem unlikely to commission a murder at the place you worked where probably many people would know you and be able to connect you with the killer.
In the last part of the film, the waitress at Winkie's is named "Betty," which raises the question of whose dream the first part of the film represents. Yes, it makes sense that it is Diane's fantasy, a dream that she awakes from after the box is unlocked. But the camera deliberately fixes on Betty's nametag (in the scene where Diane is arranging the hit), which makes me think of two related possibilities:
That Diane has taken that name for her character in the first part of the film in the way we take everything we experience as material for our dreams. Or, that the first part of the movie is actually Betty the waitress's dream. How many aspiring actresses go to Hollywood only to end up waiting tables? The waitress could be another casualty of the system. At her own big audition, she didn't turn into a seductress as "Betty" did -- she didn't give that extra ten percent. She didn't pander to the desires of the leading man (and Chad Everett was sleazy), so she ended up shlepping coffee and hash browns, dreaming of what might have been. And she is the only character in the film that would have known about the Monster/Homeless Guy in the alley behind the place. - (Rob Codey)
After watching the movie again, I would almost believe that the Winkie's scene with Dan and Herb is a flashback to a conversation that Diane overheard when she was working as a waitress there. Since the guy mentions that the Bum is the one making everything happen, she works that little bit into the grand conspiracy theory in her delusion. - (jason)