Viewers have commented on the fact that the newly-commissioned Rupert is seen boarding a train in the uniform of a high-ranking naval officer. It was explained in "Radio Times" that this was a genuine error; Paul Rhys had accidentally put on the coat intended for the character of Michael Hadleigh.
In the credits for two of the episodes they misspell the actor who plays Christopher Castle's name, instead of "Nicholas Audsley" he's listed as "Nicholas Adsley".