This is the first episode of the "Star Trek" franchise since Prototype (1996) 22 years earlier to be directed by Jonathan Frakes. In the interim, he directed Star Trek: First Contact (1996) and Star Trek: Insurrection (1998).
When Dr. Culber discusses with Tyler the tests performed on him he mentions the "Manchurian protocols". This is a nod to the Frank Sinatra movie The Manchurian Candidate (1962) (and its remake, The Manchurian Candidate (2004)). The premise of the original was a squad of American soldiers were captured during the Korean War and brainwashed to become sleeper agents.
A direct sequel to the Star Trek: Enterprise (2001) episodes In a Mirror, Darkly (2005) and In a Mirror, Darkly, Part II (2005), and prequel to Star Trek (1966) episodes Mirror, Mirror (1967) and Star Trek (1966).
When Captain Lorca is discussing navigation with Burnham and Saru, a tribble can be seen sitting on his desk.
The visual display of the Constitution-class USS Defiant matches neither the ship's original configuration (as seen in The Tholian Web (1968), In a Mirror, Darkly (2005), and In a Mirror, Darkly, Part II (2005)), nor the modernized version of the Constitution design introduced in Will You Take My Hand? (2018) and featured throughout Discovery's second season, as well as the spinoff Star Trek: Strange New Worlds (2022).