Ever gone down the slide from the upper deck of a 747? It sure looks like a LOOONNGGGG way down there. You're going to have a lot of people freeze in the doorway. Unless there's a Jumpmaster with a size 14 combat boot to "encourage" expeditiousness . . . . . I hope someone posts the video of the evac drill on the 380.
The obese ladies with the rayon stretch pants will burst into flames and start a smoke trail about a quarter of the way down the upper deck slide.
As far as injuries go, there's really no way to completely avoid those in an evac. Getting a few bumps and slide burns sure beats the alternative.