The number 'Pi' is spoken or seen or otherwise referenced several times in the story, including being used as a cell phone password in the beginning of the film, and as a number painted on a door at the end of the film, and other ways.
The mythical Greek creature known as a Minotaur (a bulls head and tail, and the body of a man) is seen in the background of an early scene, walking down the street, and then again in the last two minutes walking directly towards the camera.
The opening credits of the film are rendered in characters of the Roman (English) alphabet, but the ending credits of the film are rendered in characters of the Cyrillic (Greek and Russian) alphabet.
The Kremlin is seen in a view from the school, and an office is represented as being in the Kremlin in at least one scene.
The first filmed appearance of Evgeny Shwartzman, who portrays Nina (the redheaded trans entertainer character who falls in mutual love with the younger, one star general character who is cheating on his never seen wife).