This page in a nutshell: Anecdotes, trivia, and unreleased film information from IMDb do not meet the reliable sources guideline. The IMDb should be used only as a tertiary source for "hard data" on released films.
Citing the Internet Movie Database (IMDb) on Wikipedia raises questions with regard to adherence to Wikipedia:Identifying reliable sources, as much of its database content is user generated with minimal editorial controls. The following essay addresses the usage of IMDb as a reference source, where its weaknesses and strengths lie with regard to content and policy, and the consequent role that it can play in Wikipedia's articles.
IMDb content which is in dispute about whether it is appropriate to reference on Wikipedia:
Released films only: Sections such as the cast list, character names, the crew lists, release dates, company credits, awards, soundtrack listing, filming locations, technical specs, alternate titles, running times, and rating certifications.
Cast lists, etc. for films and television programming that are still in development or production, and have yet to premiere.
The IMDb message boards, which are inherently not reliable.
The user comments for each title (this includes user reviews and ratings), which are pure user-generated content.
Sections written in wiki-style with minimal editorial control. Those would be the FAQs for particular titles (not the database FAQ), the parental guides, and the plot synopses (not to be confused with the plot outlines or plot summaries, which are subject to editorial control).
Newsgroup reviews, which are archived Usenet postings.
The trivia and goofs sections that are based on user submissions.