The birth and death dates of Marion Davies and Fannie Brice were reversed. Marion Davies lived from 1897 - 1961; Fannie Brice from 1891 - 1951. The dates given in this film switch the dates, having Davies die in 1951 and Brice in 1961.
William Mann tells an anecdote about the "Queen For A Day" limousine pulling up in the Warner Bros. lot while Grant and Orry-Kelly were working on Arsenic and Old Lace (1944), and Grant used the "Queen For A Day" to make a cruel joke at Orry-Kelly's expense. Arsenic and Old Lace (1944) was in production in late 1941 and Queen For A Day did not premiere until 1945.