At about minute 17 when the vicar greets Mrs. Lestrange she mentions the bible verse "to everything there is a season" which he wrongly attributes to Proverbs. It is actually from the book of Ecclesiastes.
In the beginning of the film, when Miss Marple is ready to go to church, you can see a calendar on the table showing August 1951. On the calendar, the month begins with a Tuesday. In fact, the 1st of August 1951 was a Wednesday.