According to executive producer and director Simon Curtis on his DVD commentary, Dame Judi Dench was unavailable for the principal photography period, and her parts had to be filmed about two weeks before the rest of the production. Throughout the movie, Dench and Michelle Williams are never seen in the same shot, including one in which Dench shakes hands with (seemingly) Williams' hand being extended from off-screen. Adam Recht's deft editing gives the illusion that Williams and Dench were being filmed at the same time.
The reenactments scenes from The Prince and the Showgirl (1957) were filmed on the same Pinewood soundstage as the original. Michelle Williams' dressing room during filming had once been Marilyn Monroe's.
Ian Murray is the standby rigger for the film. His adopted grandfather, Jack Thompson, was the standby rigger on The Prince and the Showgirl (1957).
Judi Dench, who portrayed Sybil Thorndike, met Thorndike several times in real life. The first time was in 1958, when Dench was in "Romeo and Juliet" at the Old Vic. "She came round to see us afterwards and was so charming. We were young actors and she was lovely to us and strongly encouraging and gentle. I think they got very, very close to how Dame Sybil was in the script."
The notebook in which Arthur Miller (Dougray Scott) has written, and over which Marilyn Monroe (Michelle Williams) is seen crying, is most likely an initial draft of his play "After the Fall", which featured a character that was an unflattering version of Monroe. The play remains one of Miller's most unpopular works.