They were intentionally played in, the Beatles were experimental and pushing the edge so recorded some vocals that were played in reverse in the mix. So those, yes, you can hear when playing the song backwards but I don't believe there is any subliminal affect to the listener. It's just a creative and experimental technique that was being used quite a bit in concert music at that time - tape. They would reverse it, slow it down or speed it up to change the pitch, etc.
What's the best thing you have done for someone who was having a really bad day?