I'm on Android and the flip board icon is the second one on the bottom when in analysis of a Daily game or Self Analysis of a completed game. It looks like a square recycle symbol.
How to Flip Board in Mobile App?
Sort:
In the iPhone app, you can use the menu located at the bottom lefthand corner of the game, where there is a flip board button. Additionally, you may place both thumbs onto the game board, swipe in opposite directions (one up and one down), and the board should flip. This is probably what your son did. :)
EDIT: I just realized that you were specifically asking how to flip it in the analysis board. I checked and there is no button for flip board there, but the special swipe still works.
Martin, ingeoffrey,
Thank you. Thumb-swiping works great! Yes that's probably what my son did 
It actually works works as long as you move your thumbs or fingers in opposite directions - away from the center, towards the center, vertically or horizontally. Very cool feature.
Last night I figured out another way to do it, albeit more indirectly:
1. In Game mode, choose Flip Board from the bottom-left menu.
2. Go into Analysis mode - the board will remain flipped.
Hi Martin, I'm in the middle of a bunch of games now in a tournament so I need a method that works mid-game. But I'll use your method for finished games, thanks again.
Robert
Trying to put it in lanscape mode, not flip
Hi Experts,
I'm on an iPhone 6 Plus. My 3-year-old son somehow managed to flip the board in Analysis mode. He didn't use the menus at the bottom, he was dragging his finger across the screen.
This could be very useful but I cannot figure out how he did it. How do you flip the board, either in game mode or Analysis mode in the Mobile app? I don't see Flip Board as an option in the menu at the bottom of the board unless I'm missing something.
Thanks,
Robert