After listening, I feel the same way. I'd convinced myself when I saw it that Cascade was refering to an extended version of the first song in the flash, not the entirety of the music of the flash.
The first song is in the album titled Cascade (Beta), but I'm pretty sure it's a bonus track.
Edit: Yes, it's a bonus track along with the last song from the flash (Black Hole/Green Sun), a How Do I Live remix, and a full song for the one tune that plays after the Jade/Beq strife.
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"There's no bliss in shifting blocks around until they line up? Guess you've never played TETRIS. From Russia with FUN, mother ****er" - AbsoluteZero