I am hoping I can get some feedback here so this doesn't happen again.  I am a hobby baker who does cakes for friends and family, and have been doing this for about three years now.  I suppose my beginners luck has run out as I've had my first wreck.

I'll post pics, but this cake was in perfect condition prior to leaving my home about 3 hours prior to this party.  As you can seen in the pics it slid on itself.  My friend reports she first noticed it upon arriving home with the cake and that it progressed form there.  

I have been trouble shooting possible problems in my head, so I'd love feedback on what you all think most likely happened.

The cake was supposed to be picked up Friday for the party Saturday, so the cake was actually completed thursday late at night and had been sitting and seemed fine.  My friend had an emergency and wasn't able to pick it up until Saturday morning.  

Was the icing too thin?  It seemed like my usual consistency with a thick dam between each layer

Was it just too hot here is south Louisiana?  Possibly but I've done three other cakes recently (in the last 2 weeks) with no problems and no sliding at all and the weather hasn't changed that much in that time

Was it in the construction?  I have done the thin layers like this before with no problems, and the layer measured only 4.25" tall in total so it wasn't an excessively tall cake.

And finally I keep wondering could possibly be something my friend did in transport, like possibly sit the cake on an incline?  She claims this happened to her sons birthday cake last year (not made by me) too

Anyways I'd love some advice because I was horrified when I saw the pics!  My friend was so nice about it and didn't even mention it!  I noticed it myself when she sent me a few pics from the party, and I had to ask her what had happened to it! (Sorry for the long post!)

I'm staring at these two pictures wondering exactly what is suppose to be wrong! I see a beautiful cake on one and that beautiful cake after cutting in the other.  What am I missing?

Oh thank you I appreciate your kind comments!!  The top three layers slid off of the bottom blue layer...you can see how it all shifted in the second picture.  Thanks again!

Oh, wow, I see it now that you pointed it out! lol!  I would have never noticed otherwise.  Did it perhaps get set on something warm/hot that caused the bottom to melt enough to shift? With it only being the bottom layer, that is the only thing I can think of!  You're welcome!!! :)

ALooks like there is some wrinkling in the fondant in the top pic. Guessing it settled after you covered it in fondant, didnt settle evenly, and slid. What was your timeline? How long did the cake rest between baking, icing, crumb coating, etc? Very cute cake, btw. I like the anchor.

In the first picture, you have some bulging between the layers, which usually indicates problems with your dam. When you dam your cakes, do you leave about 1/2" from the edge of the dam to the edge of the cake to allow for settling? A good, stiff dam will save many cakes from sliding, no matter what they're filled with. My second question is, what did you fill them with? If your filling was soft (cream cheese based or even a very soft bc) and your dam isn't strong enough, the cake can slide when you move it.

Cute design, I love your writing. 

That really looks like it was on the seat of a car and it started to slide.  It is unlikely that the same thing happened twice to the same person without there being a common cause.  The friend probably thinks their car  seat is "flat enough".  It isn't.

In the future, I would strongly emphasize the importance of carrying the cake level, even in the car

Thanks for the feedback!  The cake is all buttercream with modeling chocolate accents and the filling was buttercream as well. I am thinking it must be something with the icing/dam as well.  I actually iced it once and saw the rippling so scraped it completely off let it rest longer, then made a new batch of buttercream and re-iced with the same rippling even though there was none after I scraped it and watched it to see if there was going to be bulging....I couldn't figure out why I couldn't get my buttercream smooth after trouble shooting for the source of the bulges as the filling, but perhaps it was afterall.  Thanks for the help!

Definitely try a stiffer dam and make sure you settle your cake with something weighted (I use a tile, there's a thread here that talks about it http://cakecentral.com/t/633571/my-newest-trick) after you fill them for a couple hours before you crumb coat. That will most likely solve your rippling problem and any sliding that isn't caused by car operator error.

How long did you let it sit?

Regardless of the little bulges on the side, the cake shouldn't have slid. The fact that it was "first noticed it upon arriving home with the cake and that it progressed form there"  indicates to me that it was the way it was handled during delivery.

Here's what i would suggest, from now on when anyone is picking up a cake, impress upon them that :

1) they must go straight home with the cake

2) keep it level - that usually also means no one should hold it. A good place for the cake to ride is the passenger side floor board. most people will displace a passenger to the back seat unless it's her mother in law (that's my experience)

3) Keep it cool - and don't set it in any direct light coming through a window

4) drive slow and leave a wide berth in front so that you never, ever have to push on your brakes even a little suddenly if someone in front of you gets cut off or stops. Tell them that the stops should be so gentle, that you don't feel the car do that thing where it bounces back a little

5) tell them that the cake is very fragile and look worried (lol)

Don't spend time with them in your house chatting while their car has time to get hot again.

Good luck - very cute cake

I so appreciate all of this good info!  It sat over night filled in the fridge then was iced the following day.  

AYour cake is really cute! Sorry that this happened but I bet the kids loved it anyway! Where in south Louisiana do you live? I live in southwest la!

Cake doesn't just move sideways, it has to be knocked. Sure, if your buttercream is really warm it will move a lot easier once it's knocked, but it still has to be knocked. It's simple gravity.

Yeah, that's not a dam problem, that's a car seat problem. If the cake wasn't cold and taken directly from the fridge into a sealed box then into the car it would be soft enough that being on a tilt could make it slide like that.

Thanks again for all of the feedback!  I really appreciate it!  I did advise them to keep it flat and drive carefully....we have terrible streets here, so I know I am a nervous wreck depending on where I have to drive cakes myself.  I am betting they weren't so careful!