Samuel Fuller's character is a cameraman named Joe. Fuller named him in honor of his friend and longtime cinematographer, Joseph F. Biroc.
Wim Wenders wanted to 'remake' Roger Corman's B-horror-sci-fi Day the World Ended (1955) as the film-within-the-film, but after explaining the circumstances, Corman suggested that Allan Dwan's Most Dangerous Man Alive (1961) would be a better choice. Corman ended up playing a minor role in the film, too.
In the scene where Joe the Cameraman calls home, he gives the phone number 213-874-3700. A quick reverse phone number lookup reveals the former owners of this phone number as Samuel, Christa, and Samantha Fuller. Christa and Samantha are Fuller's real life wife and daughter. He apparently gave his real phone number to the operator in the film.
On the Apple II computer Friedrichs date of birth is the same as Wim Wenders, August 14.