After the release of "Cutterpillow" in December 1995, the Eraserheads got involved again in another controversy. The media & religious groups alleged that some of their songs (along with certain songs by Rivermaya and Yano), have secret, "satanic" messages when played in reversed. Thus, the recording technique called "backmasking" came around.
In January 1996, ABS-CBN show, "Magandang Gabi, Bayan" (hosted by Noli De Castro), aired an episode entitled "Nakatagong Maskara sa Baligtad na Musika". It discussed the puzzling phenomenon of "backmasking" & featured E-Heads songs such as 'Overdrive'.
In the media, the TV show, "Balitang K" (ABS-CBN) may have been the culprit that started it all. Check out Ely Buendia's entry on 'Pillbox #3' (p. 56)
I'm not gonna list the controversial songs just because it's a waste of time. But here's a link to a blog by a blogger called Ambi Dextrose. He has an explanation/response from longtime E-Heads producer, Robin Rivera.
To date, I'm only aware of two E-Heads songs that used backmasking:
"Ed Formoso sucks"
At the 3:40 mark of the song, 'Combo On The Run', you will hear a short part that is 'backmasked'. When reversed, it says "Ed Formoso sucks". He was the co-producer of "Ultraelectromagneticpop!". According to interviews with the band, Ed Formoso abandoned the band halfway through the recording sessions of "Ultraelectromagneticpop!". This is a proof of their dismay.
"Merry Christmas Everybody Happy New Year Too"
The 1996 album, "Fruitcake" starts off with a 32-second backmasked intro before the song, 'Fruitcake'. It is actually a portion of the outro track, "Merry Christmas Everybody Happy New Year Too".
(Track 22 on CD; unlisted CD track; listed on the credits only; unlisted on the cassette tape; currently listed in all audio streaming platforms)