From Prussia with Love - S5-E1
Character mistake: Boycie is expecting a boy, but when he finds out it's a girl, him and Del argue. Del then says "I told you it was a girl, but it ain't" He should have said 'boy'. In the script for the episode, it even says 'boy'.
Character mistake: During the scene of the dinner, James (Raquel's father) states that he was in the Royal Navy and was "First Officer" (1/O). The Navy does not have this rank since it is a Merchant Navy rank. The rough equivalent of this is Lieutenant in the RN and Albert would've known this but didn't mention anything. It is also extremely unlikely that an officer the RN would still be Lieutenant after doing his full quota of 12 years service.
Chosen answer: An apparent long string of illnesses.