You may have noticed that tiny little half step slide down on that large slide towards the middle of the track.
I added that simply because the slide is 13 half steps - one full octave plus a minor 2nd - and the trombone can only slide 1 full octave (12 half steps) from where the slide started.
So the slide ended up sounding because the pitch gets clamped to one half step below what you should be playing.
To fix that, or rather nudge the player to fix that, I made the whole thing start a half step up so the slide sounds good.
Looks a bit weird, plays a bit weird, but at least it'll sound (mostly) right.

-StaticR