These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Doctor Who S 33 E 04 The Power Of Three
Fridge Brilliance: Rory's father waits near a box for four days. Maybe that's where his son got it from.
We get a reference to the Brigadier, the Doctor advising UNIT and defeating the cubes by reversing their polarity. In an episode called "The Power of Three." A homage to the Third Doctor, maybe?
Paranoia Fuel: Millions of strange cubes just appear one day, no one know where they came from or why they're here and they lay dormant for months.