Car Crash Effects Breakdown

In the latest GARANIKOR comedy short "Supplement Surprise", we had a scene where Brady gets hit with a car. Here's a breakdown to how we achieved the effect.
I didn't look up any tutorials on how to do this, I just kinda thought of doing this myself, and luckily it worked out alright. There's some minor errors in this demonstration, like a bit of green that wasn't keyed out, but that's because the actual video cuts away before those frames are used.
This was a pretty amateur execution, but I hope it gives you an idea of at least how you can achieve simple effects like this yourselves.
Here's the full video - • Supplement Surprise