Early in the film, Rick notes that, with Roman Polański as a neighbor, he's one backyard party away from getting cast in a hot new film. At this point, the audience believes that the Manson Family will eliminate that possibility. In the end, however, Tate and company survive, and Rick gets warmly received by the household, suggesting that he might indeed make friends and earn a big role in a future film.
When Rick confronts Susan, she suddenly spins and aims her revolver directly at him, but he roasts her before she can get her shot off. Rick proves himself just as fast on the trigger as the various gunslingers he's played.
Out of respect, the movie shows the real Sharon Tate on the screen in the showing of The Wrecking Crew. It can be interpreted as a nice meta-reference that of course the ticket girl and the usher take a while to recognise her, because that's not the real Sharon, it's Margot Robbie playing her.
In Rick's conversation with agent Marvin Schwarz, Schwarz notes that it's a common signifier in Hollywood to have the new up-and-coming star defeat an older one to establish the up-and-comer's credentials at the expense of the has-been. Rick's role in Lancer is heavily implied to be this in practice for him. It's significant, though, that the only scene we actually see filmed on the show is the confrontation where Rick delivers his powerhouse performance, not the one where the hero (presumably) defeats him. This is also the last scene for the show that Rick films (presumably his death scene was shot earlier). If this is indeed the twilight of Rick's TV career (if not acting career), then the filmmakers make a point of symbolically showing him leaving on a high rather than the "fall".
