Yes, I agree. It's as clear cut a case of 'mass hallucination' as you're likely to see.
It reminded me of a discussion by Zizek in The Parallax View (I recently read some, not all of that) regarding the function of the Lacanian Other in failing Soviet states: everyone living and working in them could see the system wasn't working, and everyone knew that everyone they knew thought the same, but remained convinced that a silent Other (in effect, the quiescent paternal presence of Stalin) thought otherwise and was sustaining them.
He humorously describes it as being like those scenes in Disney when Goofy runs off a cliff but takes several seconds to notice he's done so - during this time, gravity does not affect him.
You can see this going on in Invisible's posts in this thread (no offence Invis 🙂 ).
Then Khrushchev gives his "Secret Address" in 1965, or Hamilton starts giving interviews, and the whole thing starts falling to pieces, or at least everyone breathes a sigh of relief, adjusts and starts to move on.