Although I can't try another time as released, in UK, in June 2005 - so it's seventeenth anniversary.
Not Ray Romano guest stars voicing Ray Magini, also Stephen Hawking as himself like in that other episode saving Lisa from gazebo and whole Mensa thing.
The pub, Knockers, obviously a parody of Hooters. Quite a coincidence Homer meets Ray Magini who works as a roofer.
Even as Lisa points out Homer's friend "Ray Magini" as anagram of "imaginary" - throw the word "Coincidence" in her face to learn it.
Then in the end, Ray is definitely a genuine human (not a figment of his imagination), at least has genuine explanations: barman had eye-patch (could have seen Ray), Ray was "hiding" behind the chimney from Flanders? And least Stephen Hawking gives the black hole explanation between Homer and Bart at hardware store.
So all the electroshock treatment Homer received in mental institution, plus his family disbelieving him about Ray, that's all punishment for nothing?! Forcing Dr. Hibbert to fix the roof is justifiable report Hibbert to GMC / medical board, whatever it's called in USA.
As for the subplot of Santa's Little Helper at the elderly folks' home - I don't give a damn.