Easter Eggs

[Bbernardini]

Monty Python did probably the best "Easter egg" of all time - but unfortunately it really could only be made to work with vinyl. One of their LPs had, instead of the usual single spiral groove, two interleaved spiral grooves on one side, so you heard one thing or the other depending on which groove the stylus happened to be placed into.

Mad Magazine did a flexidisc like this with 8 different possibilities.

Wikipedia has an extensive list:

https://en.wikipedia.org/wiki/Multisided_record

[Rune Blackwings]

Depending on the release, Monster Magnet had a hidden video in their Dopes to Infinity cd. It was only in early release of the cd-later ones do not have it. It was said to be the band experimenting with the idea of enhanced cds

[strawberrybrick]

I did a compilation in the 90s where I had all sorts of tricks with the counter, track 0, etc... trying to think of what software I used... SoundForge/CD Architect?

[PeterG]

They list a hidden track for ELO's "Face the Music", but I tried my copies of both the original CD release and the remaster, and neither had a hidden track.

I don't have the CD, so I don't know. But I can tell you there is a hidden message on the vinyl version. At the start of "Fire on High" is a backwards message, so if you play it backwards you hear Bev Bevan saying, "The music is reversible, but time is not. Turn back. Turn back. Turn back. Turn back." Apparently this was the band's dig at the backwards satanic messages hysteria going on at the time, and the band's response to the ungrounded allegations by fundamentalist christians that there was a satanic message in the song Eldorado.

[Trane]

Not really an Easter Egg (or an anti EE, then)

But the dutch band Poetica In Silentio (I know,, not really dutch-sounding name)'s debut album (link below), they manage to put the second last track at #11 (De Dood >> The Dead) and the last one (Stop Laughing) at #18... They incremented the track counter every death knellending the Dead/Dood track.
The last track also contains a few minutes of silence as well in the middle section if memory serves.

http://www.progarchives.com/album.asp?id=14213

PS: it's a prertty good albbum too.... IF you can find it.