Hello,
so I've discovered something quite funny by accident.

In Citadels, if you save a game when you are told that a particular character is not present, and then restore it, the previous character gets an extra turn as the new character who is not present in the round.

Here is an example with comments:
The game is starting.
No architect will be present this turn.
No bishop will be present this turn.
A concealed character has been discarded.
Blue duck chooses a character.
Grandma duck chooses a character.
Choose a character:
// Now I chose the Merchant.
It's the turn of the thief.
It's Blue duck's turn.
Blue duck gets 2 gold coins.
Blue duck builds the docks for 4 gold.
Blue duck steals gold from the merchant.
It's the turn of the wizard.
No wizard is present.
It's the turn of the king.
It's Grandma duck's turn.
Grandma duck gets 2 gold coins.
Grandma duck takes the crown.
Grandma duck builds a castle for 4 gold.
Grandma duck collects 1 gold from his nobility quarters.
It's the turn of the bishop.
No bishop is present.
It's the turn of the merchant.
Blue duck steals you 2 gold.
It's your turn.
What do you wish to do?
You get 2 gold coins.
You get a gold coin.
What do you wish to do?
Choose a quarter to build:
You build a church for 2 gold.
It's the turn of the architect.
No architect is present.
The table has been saved!
Welcome to the playroom, version 3.0.0.1 [19.09.2021]. 163 players are connected at the moment.
You have joined the table.
You have joined the table.
Wait for players to join, then press enter to start the game. Press B to add bots, press Shift+B to remove bots, and press Alt+O to set game options.
Blue duck has joined the table.
Grandma duck has joined the table.
// Now, the menu options for my turn normally appeared, and I could play another extra turn as the architect.
What do you wish to do?
You get 2 gold coins.
you draw 2 cards.
What do you wish to do?
It's the turn of the warlord.
No warlord is present.
The table has been saved!
Welcome to the playroom, version 3.0.0.1 [19.09.2021]. 164 players are connected at the moment.
You have joined the table.
You have joined the table.
Wait for players to join, then press enter to start the game. Press B to add bots, press Shift+B to remove bots, and press Alt+O to set game options.
Blue duck has joined the table.
Grandma duck has joined the table.
// By repeating the same action again, since the warlord was not present, I get another extra turn as the warlord.
What do you wish to do?
You get 2 gold coins.
What do you wish to do?
Choose a quarter to build:
You build the imperial treasure for 4 gold.

After this, the game normally continues on.

Thanks.