- Harsher in Hindsight: Katie's statement: "I haven't killed anybody... yet."
- He Really Can Act: It's unlikely you've ever seen anything with Wyatt Russell in it prior to this episode, but his acting chops in Playtest rival that of his father's.
- Idiot Plot: Saitogemu, and Katie in particular, seem extremely negligent in their security and safety precautions. Why allow the phone in the room at all? Shouldn't they be testing this in a shielded room?
- Narm: The ending is heartbreaking, but Katie typing "CALLED MOM" in the report feels like a pretty cheap and manipulative gut-punch. It's clearly supposed to be an ironic reference to Cooper finally "calling" his mom back after ignoring her calls for so long, but the wording sounds unnatural and forced compared to something like "called out 'mom'", "yelled 'mom,'" etc.
- Shocking Swerve: In the last ten or so minutes of the episode, it's revealed that the experimental technology has gone too far and left Cooper permanently traumatized and without memories. It's then shown that that was part of the game and he's safe in Saito's office, ready to go home at last; he leaves and finds his mother has developed Alzheimer's just as his dad did and no longer remembers him, which is when that too is revealed as part of the game, only this time it's gone terribly wrong and killed him due to interference from his phone being called by his mother, as it was still on after taking the photo of the device. The bleakness is nothing new for Black Mirror, but the inability to wrap the plot up tidier is.
- Visual Effects of Awesome: The bully-spider thing really looks believable. It is currently the page image for Black Mirror's Season 3 Nightmare Fuel page.
- The Woobie: Cooper. Poor, poor Cooper.
- Cooper's mom as well.
YMMV / Black Mirror: Playtest