After killing a zombie there is a seemingly random chance that its dead body will have collision, causing the player to get pushed around and potentially get inventory/hand slot bugs.

From what I can tell this is completely random, I have tried to spot similarities between each occurrence but can't find any.

I'm primarily using a 2 handed weapon for the kills in the video but it happens with other weapons as well, such as fists as you can see in the final clip, so I don't think this has any correlation.