The part of Lucius in "Julius Caesar" that was played by the character Richard Samuels in the film was actually played on the production's opening night by an actor named Arthur Anderson, who was making his Broadway debut. Anderson is best known as the voice of Lucky the Leprechaun, the mascot of General Mills' Lucky Charms cereal, a part he played for 29 years.
Lindsay Lohan was the top choice to play Muriel Brassler. She screen tested for the role and was close to signing a deal shortly before filming began. However, the producers found her to be impossible to insure due to her ongoing legal troubles at the time of production. They decided to replace her with Kelly Reilly.
The author of the source material did not know anything about Arthur Anderson (the original actor who played Julius Cesar). He based it on the premise of a still photo of the teenage Anderson playing alongside Welles opening night. In reality, Anderson did not get fired and not only made it through the entire run of the show but was cast in two more of Welles' plays.
A common mistake in movies and TV, fire sprinklers are activated individually - a match held to one would only cause that particular sprinkler head to open, and not all of the sprinklers as shown in the movie.
Richard accompanies Orson to 485 Madison Ave (CBS) for a "recording session" for a radio show ("The First Nighter" program). At this time (1937) and until the late 40s network programs were broadcast live, never recorded. Most programs were produced live twice, once for the East Coast and three hours later from the West Cost.
Orson Welles: Do you know Booth Tarkington's "The Magnificent Ambersons?" Tarkington was a family friend. The character of Eugene, the inventor, is based on my father who died when I was fifteen. My mother when I was nine. "Ambersons" is about how everything gets taken away from you.