I know about hidden tracks on CD's, but are there examples of hidden tracks on cassette/ vinyl?
Jack White has a habbit of including hidden tracks and other features. Here's for instance his latest album Lazaretto:
The 11-track album on White's label Third Man Records, includes different mixes and sequencing to the digital version, and will play at 33.3rpm as normal. However two secret tracks hidden in the centre label will play at 45 and 78rpm respectively – a repeat of the trick White pulled with his Dead Weather supergroup and their album Sea of Cowards.
Side A meanwhile demands that you place the needle on the inside of the record as it works its way outward, eventually getting caught in a perpetual locked groove at the outer edge (the more jaded White fan might suggest that you won't be able to tell when said groove begins). The first song on Side B however, has two different intros, one acoustic and one electric, which differ depending on where the needle is dropped. The two grooves then blend into one halfway through the song.
If that wasn't enough to play with, there is also a hologram on Side A hand-etched by artist Tristan Duke, featuring a spinning angel appearing to float in the blank area between the groove and the label. Side B is given a matte finish so it resembles a shellac 78rpm record.
Yes, you need to destroy the center labels to play the hidden tracks. Billboard has a video.
Monty Python's Matching Tie & Handkerchief may qualify, as entire sides were 'hidden' by two methods.
Both sides of the album had the same label, claiming it was 'Side 2'
One side had dual concentric grooves, so which tracks you heard was dependent on which of the two grooves you hit when dropping the needle.
It was referred to at the time as a 3-sided record.
C+C Music Factory's Gonna Make You Sweat album on cassette had a hidden track. The cassette said that "Bang That Beat" was the final track on the tape, but if you let the cassette continue playing for about 20-30 seconds past the end of that song, then you heard the "Shade" song start playing.
- "Wish You Were Here" 6:35
- "Comfortably Numb" 9:29
- "Run Like Hell" 8:36
- "Soundscape (Ambient piece played before all concerts)" 22:00
In case of vinyl, the contents in the locked groove will be in many cases a hidden track (discussed here).
One of the first and most famous hidden tracks is on The Beatles' Abbey Road. "Her Majesty" begins 14 seconds after the last song listed on the album jacket ("The End") and runs 23 seconds long. It is often considered the first example of a hidden track in recording history. Released in 1969, this was long before CDs.
There have been lots of albums featuring hidden bonus tracks since, released on every format you can think of, using various techniques. Wikipedia has an article about hidden tracks that discusses the techniques and notable examples.
From Mew's album No More Stories Are Told Today, I'm Sorry They Washed Away // No More Stories, The World Is Grey, I'm Tired, Let's Wash Away, the track New Terrain, when played backwards, is a different song called Nervous. I'm not sure if it strictly qualifies as a "hidden" track - it was added as a bonus track on the vinyl edition, but since it's the same audio played in reverse, hiding the song is independent of the media it is recorded on.