Bob Hovey’s review published on Letterboxd:
Unusual and delightfully offbeat psychological sci-fi thriller could be described as a feature-length Outer Limits episode with a good dose of Kafka thrown in. Jake Gyllenhaal gives two excellent performances, playing a reserved college professor (Adam) who accidentally discovers he has an exact duplicate, a somewhat tightly-wound actor (Anthony), and decides to contact him... an action which produces serious repercussions for both of them, as well as Adam's girl friend and Anthony's wife.
Subtle direction from Denis Villeneuve propels this disturbing and smartly-presented story ... the miasmic yellow-green grading and deliberate pacing produces an oppressive and uncomfortable setting, and we are continually thrown off balance by the ambiguous narrative punctuated by dreamlike sci-fi touches like the giant spider-like creatures that occasionally appear.
While Adam is the first of the two to speak and we seem to spend somewhat more time with him, there is no certainty that Adam is the 'real' individual in this story... there are scenes in which we aren't initially certain who we are looking at, or which one is real, or if indeed both are real. As a psychological thriller, the presumption would be for one character to be a figment of the other's imagination (since they are precise physical duplicates, right down to their scars), but interpreted more broadly as a sci-fi story, one of these characters could be explained away as an alien shapeshifter or visitor from a parallel reality. Or it could be pure fantasy... an allegorical tale dealing with the political questions that Adam and his history class are exploring throughout the film. But in whatever way you might chose to interpret what you're seeing, this remains an intelligent and stimulating film, one that probably deserves more than one screening.