Queen (and other groups of that era) were famous for overlaying (a little different than overdubbing) a recorded track dozens of times to get that big spatial effect. Of course, this doesn't work in the digital editing medium because it was the imprecision of the tape medium that created just enough phasing to make it work.

I don't know if there is a plugin to emulate this effect; if there is, I'd like to hear about it.

You could approximate it by overlaying a track in ACID or Sonar that had some "swing" on each track, de-tuning each track, and off-setting some of the sounds, but ain't no way you'll get the cardboard box thumps that Roy T Baker created for this record (yes, it's a cardboard). Trivia; He has a vacation home in Lake Havasu, AZ and has a small 'vacation' studio in which he plays with Sony Vegas for audio-only.