I also saw the (1979?) movie (many times during the 80s and 90s), though I forget everything but the song (I seem to remember it was set in the post "race riots" period).I always thought about "open borders" when I heard the repeated "mutual understanding" words, as well as other parts.
Now, here is the ironic part:
Ronald Reagan also used the words "mutual understanding" when he debated Bush for the GOP nomination in 1980. He was talking specifically about how we should "open the border both ways" with Mexico. Now, after around 1987 (if I did not know slightly earlier), I knew that President Reagan was for "open borders", but I never knew about nor did I see his Texas Republican Primary debate with Bush.
Reagan got what 95% of Republicans and Democrats surely did not get.
I was always fond of saying "hippy is short for hypocrite", because I knew some of the 1969 Woodstock jokers personally. I know just how racist the "peace and love" rednecks were and (probably STILL) are.
Look at the Harvard-Harris 2018 polls.
Those 65 year's and older are about 88%+ against open borders.
The 50 to 64 age group is 84% opposed.
(Under 50-year's-old Americans are 66% opposed, but the younger you go, the closer to 50-50 you get)
Ronald Reagan remains our best President, because he "got it".
That is my opinion and I am entitled to it.
EDIT MESSAGE: Forgot to mention that the Reagan family had some fans of astrology from the top (the President and Nancy themselves).