A citation, also called a reference, is needed to verify content. All content, including categorization, on this database's article namespace must be verifiable and unsupported statements could be removed by any editor. Exclusive screenings prior to public shows can't be used as information sources because they won't be open to peer review.
Citation footnotes can be easily added to article text by using the R template. A footnote should be placed right after the text it applies, after a possible punctuation (except dashes), without any additional spaces before or between adjacent footnotes.
As for web pages, they are inserted into footnotes using the Cite web template.