English English came first...

Google "Bananas in Pajamas" then "...in Pyjamas". You get far more for Pyjamas. Therefore Pyjamas it is.

Case closed.

Anyway, it's an Australian program and they, like us, spell it as "Pyjamas". Just 'cos you're America doesn't mean that you have to have everything spelt your way. American books and films and whatever we get haven't got everything spelt in the English way, why should you have everything spelt in the American way?