In the 1950's, the Mass would have been in Latin in a Catholic church, but the opening scene shows the priest saying it in English.
The motto on the sign for Upton Seminary (right after the opening credits) contains the motto "Ad Maioraem Dei Glorium" (For the greater glory of God). This is the motto for the Society of Jesus (the Jesuits) and would not have been used at a diocesan seminary.
It is also doubly misspelt: it ought to be AD MAIOREM DEI GLORIAM.
It is also doubly misspelt: it ought to be AD MAIOREM DEI GLORIAM.
As Sid is driven away in the police car a "wireless" antenna is visible on the car. Wireless Radios were not installed until the 60s.