In Night at the Museum (2006), Teddy (Robin Williams) says the exhibits have been coming to life since the tablet of Ahkmenrah (Rami Malek) arrived in 1952. In this movie, Cecil (Dick Van Dyke) says the tablet arrived in New York City following the expedition to Egypt in 1938 (depicted at the start of this movie). In the first movie, Ahkmenrah says he spent some years in England at one of the universities, suggesting he was sent to England for many years before he arrived in New York City.
The musical score in the beginning of the movie resembles the song "Moondance". This is fitting as the moon's light is part of the plot and both the song's lyrics and the movie share themes of the night.
Although Night at the Museum (2006) contained hints that Dr. McPhee (Ricky Gervais) was aware of the magic that occurs within the exhibits, the sequels discarded this possibility completely, and made McPhee out to be completely in the dark. In this one, he is surprised to learn the secret only at the end of the trilogy.