I had a 2 tier cake for a 1st birthday that I did this weekend and the monkey started falling off the cake an smashing it in...I thought it wouldn't weigh it down since rkt are so light but I guess maybe it needed a card board base to sit on...it had a dowel rod though it. it was suppose to have brown hair as well but fell over as I was about to put it on the cake so I had to wash it off and leave him pink even though all his accessories were brown...Also I had a problem with my polka dots sliding down the cake...I am new to mmf so maybe that's it but I have never had a problem with that! Everyone said it was amazing but It was a huge disaster to me.

Throw something?

it's frustrating,i know,but we learn from our mistakes. just keep trying! i usually use a cake board cut down to size if have a rkt structure to put on top of my cake. rkt can be heavy depending on how big your structure is.
i also use a couple of dowels underneath it to support the weight of the rkt's.

I try not to underestimate the weight of things on cake. I did once . I usually put a piece of cardboard and plastic cake supports under it or some dowels depending on how big it is. Better to be safe then sorry. Sorry this happened to you.