I think that the card apearing on the top is a little excessive. I have been doing the same effect for a bit and how I do it is "push" the card through the box and it "Falls" out the bottom. Tried to explain as best I could without revealing, if you have any questions feel free to PM me
Good routine, nice location. It was a little extreme in showing the card melting through the box. Try a Window Change type deal, that way the back of the card shows and there will be more suspense.