Once of my top pieces of advice is don't know everything to begin with, that way you don't end up tripping yourself up.

Also remember you should be able to trust your players and co-opt players into your schemes. Players love knowing things others don't. Just remember you don't have to tell them everything (or all of them the same thing).

In a recent game set in the first world war we played out the first two thirds of game straight. We then revealed it was a memory of one other players in an asylum by taking the players out of the room one at a time to explain the situation: until one player was left without explanation. The game continued as before but the players changed the dynamic of the game themselves with their new knowledge.

It worked partly because we (the GMs) didn't know at the beginning who would be the survivor, we let the story work itself out.

My top suggestion is don't have everything decided to begin with, that way you can reduce the chances of tripping yourself up. These sort of plays can get complicated so make it as easy as possible for yourself.

Also trust your players, then you can co-opt them into your schemes. Players love knowing things others don't. Just remember you don't have to tell them everything (or all of them the same thing).

An example of of both of these: in a recent game set in the first world war the first two thirds of the game played out as a normal game (Battle of St Julien if you want to know). We then revealed it was a memory of one of the players in an asylum, taking the players out of the room one at a time to explain the situation: until only one player was left. The game continued as before but the players changed the dynamic of the game themselves with their new knowledge. The focus of the game slowly shifted onto the remaining player.

It worked partly because we (the GMs) didn't know at the beginning who the the survivor would be and we let the story work itself out.