Backward messages goof

Early on in the movie, Cronauer puts on a record and finds it on the wrong speed. He has some fun playing with the speeds a bit, and then pretends to play the record backwards, mimicking it saying, "Freddie is the devil...Freddie is the devil".

The film takes place in 1965, and, to the best of my knowledge, backward messages on records were a generally unknown phenomenon until the Beatles famously made use of this technique several years later.

Furthermore, backward "devil" messages on records did not become an issue until a few more years down the road in the 1970s.

Has anyone else here noticed this?

Sam