A freudian slip.
Rather than weigh in with a definitive answer, Christopher Nolan carefully protects the ambiguity of the film's ending, allowing movie fans and film scholars the space to debate what's real. The writer/director did reveal some of the movie's influences, however. In addition to the myriad myths, music, and religious history incorporated in Inception, Nolan cited the work of Ian Fleming, the Wachowski siblings, and Sigmund Freud in a 2010 La Times interview.
The dream team.
Nolan relied on his own experiences rather than volumes of research when it came to dreams as he penned this passion project