While the characters are recalling the last things they remember before being in the Cube, Geraint Wyn Davies' character, Simon, states he was in New Haven. When the screen divides into different views, the shot on the right/upper right of the screen is an alternate take from another Lions Gate film Davies had a role in, American Psycho II: All American Girl (2002). The similar shot in American Psycho II can be seen shortly after 1 hour 6 minutes into that film.
The trivia item below may give away important plot points.
When Colonel Maguire is killed, the effect of the wall of energy crashing into him is actually just created with a vacuum cleaner stuck on exhale (to blow his clothes around) and CGI, for the wall itself.