I think it should be obvious by now that Rick never left his family then returned. That Rick is probably dead. The Rick we know just jumped dimensions for an as yet unrevealed reason.

The 1970s was the Rasputin of the 1980s.

How well did you know what they were mocking?

If you didn't laugh at this episode, the reason you didn't is that you don't like sarcasm.  This is the most bitterly sarcastic episode I've ever seen and it's filled with jokes.   Of course, if you don't like sarcasm, you're not going to enjoy this a bit.