Mention in John Houseman autobiography

The film shot for an abortive stage production is discussed in John
Houseman's memoir "Unfinished Business," which I highly recommend.
"Orson's production idea for Too Much Johnson included two filmed
interludes -- both chases: the first, a prologue... a wild chase
through the streets, parks and waterfront of New York City; the second,
a comic manhunt through a Cuban jungle to be created in Palisades
Park." The production did not reach the New York stage - it was
withdrawn after tryout at Stony Creek Summer Theater in Connecticut.

The review of the film that appears here on IMDB is done by the late F. Gwynplaine MacIntyre, a guy who is believed to be a hoaxer, reviewing many "lost" films - see comments on the talk page of his Wikipedia article.

However, there is a claim on Wikipedia that some footage from it was screened at Pacific Film Archive in Berkeley in 2010. It's not fully referenced, however; one calendar listing mentions "Plus rare footage from the PFA Collection."