Interior of tour bus has sky lights that don't appear in exterior shots of vehicle.
The primary film spoofed in the screen tests is The Shiek, a role that Valentino himself detested. In fact, the only reason he returned to the role at the time this film takes place is that he needed the money to pay his debts.
This film is supposed to take place in the 1920s silent movie era, yet the movie extras riding in the bus to their location sing-along to "Shuffle Off to Buffalo", a Harry Warren-Al Dubin song written for the 1933 sound film "42nd Street."
The "audition" record that Rudy listens to is obviously an LP running at 33 1/3 rpm. LPs would not be invented until the late 1940s.