Mary tells of the time when Sheldon bought uranium from a warlord in Chad. She says he was 13. In Young Sheldon (2017), they detail this and it happened in the first season when he was 11, not 13.
When Leonard hugs his mother, Beverly says "Oh my son." Leonard replies "Oh my mother" and Penny responds with "Oh my God."
Mary doesn't even react to the blasphemy, much less chastise Penny for it. This is completely out of character for her, a devout Christian.