The Doctor and Andy travel back to the 70s (or is that the 80s?
) while Liv and Helen discover more about two of the Baker Street tenants.
- Double-Meaning Title: Refers to both Tony and Ron dating while serving with UNIT, as well as the UNIT dating controversy mentioned early in the story.
- "Groundhog Day" Loop: Andy’s investigation of the device hidden by Tony is hampered by one.
- Self-Serving Memory: At one point the Doctor talks with the Brigadier of the past era about his current situation. When the Brigadier quickly understands the Doctor's explanation about how he's caught in a time loop, the Doctor muses that his third incarnation let his bitterness over his own exile colour just how capable his UNIT colleagues were, such as underestimating how much the Brigadier would understand of such a situation.
- Shout-Out: Andy compares the "Groundhog Day" Loop to the trope namer, as well as Buffy, Star Trek: The Next Generation and X-Files episodes.
