When Mester Hansen gives his date of birth he claims to be a leap-year child and says he was born on 29 February 1922. However, 1922 was not a leap year and thus did not have a 29 February (1920 and 1924 were leap years).
At the end of the movie, Mester Hansen is bragging about stealing the Bedford diamonds at Rådhusplassen and the Ming vase at the Nationalteatret, to Holm's surprise. But how did Mester Hansen, and Holm, know that these events even took place, and where? The only ones that had any knowledge about these coups are Egon and his gang, and they never told anybody about them.