For the location filming at Latchmere Prison (where Dr Patterson works), the crew's Movement Order gave the instruction: "No ladders to be left unattended please, they must be locked on the trucks when not in use (not a joke!)".
Hathaway delivers this line: "Where is the wisdom we've lost in information?" This is a compression of two lines in the opening of "The Rock: A Pageant Play" by T.S. Eliot: "Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information?"
When Lewis mentions he doesn't like "Professional Geordies", this is a huge meta in-joke, as Kevin Whately has had a long career playing characters, that happen to be "Geordies" - a slang term used to describe people from the Newcastle area, in the north of England. Usually a term itself a sub-category of the slang term "[England] Northerners".
Owen Teale is actually Welsh, not a Geordie
The prison warden warns Lewis by saying "Mind how you go." This phrase becomes common statement in the prequel series
Endeavour.