The Occulus is powered by a contained, albeit reduced, supernova. In Dr. Who the Time Lord's technology is powered by a captured star held at the moment of collapsing into a black hole. A supernova is what collapses into a black hole. Time Masters and Time Lord's have identical power sources.
Mackenzie Gray (the Time Master who speaks to Savage at the end) is no stranger to the DC Universe. He played an older clone of Lex Luthor in Lazarus (2010) and also played Jax-Ur in Man of Steel (2013).
At the source of the Occulus, the team is intercepted just in front of a large, oddly domed building. It is the Bloedel Conservatory, a greenhouse and aviary, in Vancouver. Despite having opened in 1969, the Bloedel is still a very popular filming location for futuristic sci-fi.
Tabula rasa is a Latin phrase, literally means "blank slate", meaning, an absence of preconceived ideas or predetermined goals; a clean slate.
The Time Masters' power source is called the Oculus. Arthur Darvill's costar on Doctor Who, Karen Gillan, appeared in the movie Oculus.