Free movement across time is a recurring theme of the film. The central character's name is Nemo, which when spelled backwards is 'omen', a foretelling of the future. Further, his main love interest is Anna and his daughter is Eve, both of which are the same when read in reverse.
Nemo is Latin for "nobody". That name may remind people of Homer's epic; Odyssey, in which at some point, the Greek hero, Odysseus and few of his men are captured by the cyclops, Polyphemus. When asked about his name, Odysseus replies his name means 'nobody'. Later, when Odysseus and his men attempt escape, they stab the cyclops in his only eye, with a burning stake. The injured cyclops cries for help, but when his friends arrive, and ask who did this to him, Polyphemus replies: 'Nobody! Nobody stabbed me in the eye, and nobody escaped!' His friends, of course don't take his story very seriously, and leave - Odysseus and his men having successfully escaped.
While on a break from filming the Neanderthal scenes, Sarah Polley received a call from a friend, who informed her that a Toronto Star reporter had discovered that her biological father was not Michael Polley, but Montreal film producer Harry Gulkin, whom her mother had an affair with in 1978 while performing in a play at the Centaur Theater in Montreal. Sarah, who had already discovered the truth herself, contacted the reporter and ran outside to a park bench in full make up and began crying as she convinced the reporter to sit on the story as she had not yet told Michael and wasn't sure that she wanted to. The reporter agreed and afterwards, Sarah decided to create a documentary film about her mother and the events that led to her conception and her family learning the truth - Stories We Tell (2012).
The trivia items below may give away important plot points.
Anna, Elise and Jean are all frequently dressed in colors related to their story with Nemo. Anna is dressed in red, which is commonly associated with love, Elise in blue, which represents depression, and Jean in yellow, the color of greed.
During one of the earlier scenes where Nemo wakes up with possibly Elise he heads into the bathroom but hesitates when switching the light on. During Lucid dreaming nothing happens when you switch on a light however it then becomes clear you are dreaming. It's as if Nemo knows this and was awaiting the results. The word architect is used at one point & the constant awaking and false awaking are also heavy themes of dreaming.
The child/teen versions of Nemo and Anna had British accents but when they reunite years later, they have American accents. This was probably intentional due to the various timelines maybe getting confused by the old Nemo.