Scott's foster parents' house had Sanitas wall covering with the plaid and wheat pattern in the kitchen area, which wasn't available until after 1983.
Scott sees the autobiography book 'The Wonderful Private World of Liberace' for sale in a bookstore while a newspaper article nearby displays a headline of Rock Hudson's death which has the date October 3, 1985. The Liberace book was in fact published in May 1986.
In the movie, both Liberace and his mother note that his first name was "Walter". Liberace was born Wladziu Valentino Liberace (Wladziu being the Polish form of Walter), and went by the name Walter through his twenties, but used only his last name as his stage name for most of his career.
At the funeral mass at the film's end, the congregation's response to the priest's opening liturgical greeting "The Lord be with You" is .."and with your spirit". This is a well-known change made about 20 years after the funeral - which took place in 1987, when the liturgical response would still have been "And also with you."
Liberace's mother is playing a slot machine at the beginning of a scene set in 1981. She died in 1980.
The wheels on the Mercedes 450SL that Bob drives in 1977 were not introduced until 1986 on the 560SL.
Towards the end of the film, there is an exterior shot of Palm Springs city hall which shows a modern dome CCTV camera.
In the shopping montage set in 1977, a California license plate with a 1AAA111 format is shown. California did not use this format until 1980.
The tailor uses the wrong end of the tape to measure Scott's waist during the montage where Liberace takes him shopping for a suit.
Liberace plays the piano while tapping his right foot. The piano is normally played while engaging the pedals to enrich the music produced, so ignoring the pedals is something a pianist would not do.