Not sure how to word this exactly but is there a kind of 'counter harmony' vocal in Need Your Loving Tonight? I'm sure I can hear a very quiet "never woo hoo" sung by Fred when the main vocal plays "I said I'll never, never be angry with you". You could probably call it a backing vocal. It's buried in the mix, but audible when played loudly (or probably if you have surround sound mix and can isolate the vocal).
I hear something similar in Coming Soon.
That one sounds like someone saying "Dennis".
Mixed with Another One Bites the Dust's supposed "It's fun to smoke marijuana", The Game could be Queen's Secret Messages album :)
Rick wrote: Who sings/says the 'out of control' bit near the end of Headlong? It doesn't sound like any Queen member, although my guess is Roger.
Sounds like Brian to me.