It sounds to me like all they did with "Isn't it midnight" was take out Lindsey rhythm guitar part to imply it as a "different mix".
The audio of "Stand back" is taken from the "Tango in the night" video concert release (which is apparently coming out on DVD in Oct.
)
"Trinity" was another good unreleased track probably from the FG sessions but could be from the BT sessions.
Please take note though that what is billed as "I believe my time ain't long" (version wise) is actually "Dust my broom" from the "Mr. wonderful" album (and not from FM's first single as the notes claim).
Also be aware that what they claim to be an "unreleased FM track" called "String a long" is wrong. Though it could easily masquerade as one since PG, JS, DK, JM & MF are all playing on it, it still only was released to the world as a Jeremy Specner solo track and yes, this same exact version of this track WAS previously released as it was taken from his seltitled 1970 Reprise album.
The audio of "Not that funny" is (sort of) the same version that appeared on the Mirage video concert release (as there are parts of the song here that aren't in the video version and there are some parts of the track that are in the video version that aren't on the one on the box set).
I think everyone else covered all the other major stuff so...
Hope that helps.
John