"Room of Riddles is actually a real good excuse to get anything we find cool and inspiring", says one of the Room of Riddles developers. The story goes that these plane miniatures where amongst the first things bought when building the first escape game in Amsterdam.
Once a guest who solved the riddle with the airplane, gut stuck in the game. After the game we found he used the wrong airplane type code. He stated "they don't fly these anymore, so I kept pressing the number of the common type these days".
Our bad, we're not that expert ;-).