Wind Up Raptor Boost (like it's name) winds back first before moving forward. There's a lot of moves that can break and/or reverse the momentum you currently have from knockback too.
That being said, what I'm seeing here is that instead of the Wind Up Raptor Boost pulling backwards (away from the direction you're facing), it started winding up in the direction that Falcon was headed before launching him in the same direction-- indicated by the slow glide that happened before the momentum shifted. I'm sure it was a momentum break shenanigan, but that's some really interesting stuff. It's possible that you B-Reversed it somehow while momentum breaking. I'll have to see if I can replicate it sometime.