- Fridge Logic: Everything with regards to the letter being a Chekhov's Gun. Why didn't Gregory throw it away? Why did it never occur to Paula that the handwriting is similar to Gregory, which she’d probably seen a few times?
- Memetic Mutation: The term "gaslighting" has become a byword for Mind Rape tactics used by domestic abusers. Ironically, tampering with the lights and making Paula "hear noises" were the two aspects of Gregory's abuse he probably did unintentionally.
- Retroactive Recognition: A 17 year old Angela Lansbury makes her film debut as Paula's maid.
- The Untwist: Gregory being the letter's sender or his accomplice and Alice Alquist's murderer becomes painfully obvious once the letter is brought up.
- The Woobie: As Paula's constant undermining by Gregory takes its toll, it's hard not to want to give her a reassuring hug.
Paula: You mean we're not going to the theatre?