Certain scenes have aspects of reality in them. For example, the famous bacon-taped-to-wall scene grew from one of the houses they were filming in, in which the occupant actually did tape pieces of bacon to the wall.
The character Tummler was a spraypaint-sniffer in real life as well, and Harmony chose him to play one of the main characters, who inhales glue with Solomon.
An F5 tornado did hit Xenia, Ohio (the film's setting) on April 4, 1974.
It's kind of like things which could happen in real life, or which do happen, but twisted and fired off in different angles, creating this bizarre tapestry of events.