DB here:
Bingo! Crowdsourcing pays off. Alert blogger Ivan Paio [3]found the original poster that’s tucked into the Magnificent Ambersons frame! It confirms that Welles used not a film poster but one advertising a stage show…that could have played the Bijou in 1912.
If you’re not familiar with our quest, you can go here [4] and here [5] and here [6]. Be sure to visit Ivan’s site [7] for details, and give him a big hand.