Sigmund Freud recalls to Anna Freud their previous meeting with Albert Einstein where Einstein says that the definition of insanity is doing the same thing and expecting different results. Though this is a quotation often attributed to Albert Einstein, it more likely originates from Al-Anon and Narcotics Anonymous groups in the early 1980s.
Lewis refers to JRR Tolkien as "John". He was known as "Ronald" to his friends.
Lewis is shown researching the Gospels while a woman who appears to be his wife calls him to bed. This film takes place in 1939, but Lewis did not marry Joy Davidman Gresham until 1956. The woman was actually Janie Moore, who Lewis lived with until 1949.
About half way through the film, Anna Freud's lover, Dorothy Burlingame, tells Anna that her relationship with her father (Sigmund Freud) is marked by "codependency". This term was coined in the 1970s, and like the apocryphal quote attributed to Albert Einstein in the film came out of Alcoholics Anonymous.