Basically, when your character is animated, your character will still have collision in its body parts. So if you were to, for example, slide down but have your character dip in the floor a little, this happens :
I think this is more the way you’re implementing the animation rather than an issue with collisions. The only real limbs that should give you collision grief is the head and torso, which have their collide property set to true every frame.
You could fix this by putting the head and upper/lower torso parts into a collision group which doesn’t collide with the default collision group for the time the animation is playing.