1. The first letter of each of the main character’s first names – Dom, Robert, Eames, Arthur/Ariadne, Mal, Sato – spell the word DREAMS.
2. The “Penrose stairs” (with a woman perpetually picking up papers) that Arthur shows Ariadne is a reference to a lithograph print by the Dutch graphic artist M.C. Escher. Escher is well-known for his drawings exploring optical illusions and real architectural, mathematical, and philosophical principles rendered in fantastical ways.
3. When Cobbs gave Ariadne the puzzle test, Ariadne’s final solution was a diagram of King Minos’ Labyrinth. Ariadne is the name of King Minos’ daughter in the same mythology.
4. The word “Cobol” from Cobol Engineering, the company Dom Cobb worked, is actually a high level language for business data processing.
5. When explaining why he thinks implanting an idea is not possible, Arthur says “don’t think about elephants” to actually make Saito think of them and thus “insert” an idea into his mind. The line is a reference to the title of a famous cognitive semantics book, ‘Don’t Think of an Elephant’ by George Lakoff. The book describes conceptual framing, the use of certain words to literally insert certain ideas about a subject into the listener’s mind in a surreptitious way, e.g. implanting the idea that taxes are a bad thing by using the phrase “tax relief.”
Read more Inception facts on IMDB.