There was a MASSIVE air bubble in this one. And the pin was poking out the side because I held it at a funny angle. The problem wouldn't get solved no matter how many ways I tried. My friend suggested I fill most of it with liquid fast cast, then mix talc powder with more fast cast and turn it into a paste, then pour it on the top and squidge it on the shoe. AND IT WORKED BEAUTIFULLY. yay!
By the way, the parcel tape is poking through on this one because it's the right shoe, the mould was made for the left shoe, but the difference is quite small so I'll just filler over it before I remould it.