* ''Primer'' is very obviously brilliant in many ways, but it's also brilliant in a very subtle way. The first time I watched it I felt very confused at the end, but like that was OK, and the artistic intent - the movie captured in a very tangible way the confusion the characters felt travelling through time. Later, as I watched it more times, I started to understand what was happening, and at some point, it hit me: the movie gives the viewers the experience of the characters travelling through time, and our repeat viewings are their repetitions of the same events. We keep watching it again and again and having a different perspective on it each time, just as the characters experience the same events over and over again, gaining new insights into what's happening.
* The name. It's a ''primer'' (information given to bring one up to date on what's happening).
** And [[http://en.wikipedia.org/wiki/Prime_%28symbol%29 prime]] is also used in physics for when a variable changes slightly. Not only does the box send them to a slightly different time, but it's also a slightly different 'them'.
** "Prime" also means "first." Once Abe and Aaron begin working at cross purposes, each is trying to travel back further to get the edge on the other; each is trying to be primer. Their names reflect this too: both are names that can be reasonably expected to be first in an alphabetic list. But as long as it's spelled that way, "Aaron" will always come first.
* One of the major themes of the movie is discoveries often being accidental and unceremonious; the creators mention penicillin as an example of such a major and accidental discovery. Abe and Aaron discover they have a time travel device via a weird pattern of fungus growth, which parallels the discovery of penicillin.
* The boxes are modular so they can put one inside another as much as they want. The toy they test the machine with is a Russian doll.