Bedtime stories have gone too far

Ok, so we've gone through all of Alex's books so about a week or so ago we started making stories up. He liked it a lot at first but now HE LOVES IT.
Too much I think - its at the stage where he asks for the story before we finish reading his real books and takes over the story telling after only a couple of minutes. He gets so excited by the story that he sits upright with his eyes wide open ready for the next part of the tale. I think we're going to have to switch to stories about paint drying.
Here's the drift of the story as it stands today:
Alex finds a secret door in the cleaning cupboard. Its dark inside but Alex gets a torch and then calls for Daddy to come with him. It eventually leads us to a beach (thanks, CS Lewis). We throw stones and then notice a space rocket close by. We knock on the door and the rocket man asks us to come in and tells us that he's in a good mood so he'll take us wherever we want to go. <Ok this is where Alex goes a bit O.T.T.> Alex asks the rocket man to take us to go and get:

• Mummy and Big baby (Emma)
  
• Baba and Deda
  
• Nana
  
• Deda Mike & Dee and the dogs
  
• Timon, Pumbaa and Simba from the Lion King
  
• The bear (Baloo) and Bagheera from The Jungle Book (NOT Kaa or Sheer Khan)
  
• Peep, Chirp and Quack from Peep and the Big Wide World
  

Now we take all these guys up to the moon, where we meet:

• Aitken Drum
  
• Michael Finnegan
  

Who both live on the moon (?!)
Its a crazy story and I know its just going to get longer and crazier. Help!