Here's what's childish:
o lamecube reference, but i guess they needed to call it something
Here's what's witty
o Sarcastic title screen "Super Double Sunny World". Thought it was hilarious.
o Mario, Princess, Yoshi, that Puffy thing. Super cutesy backgrounds, stars, and music.
o Over the top parody of jumping motion inherent in these games and fruit eating.
o Final collection of dozens of coins, fruits, etc.
I thought the caricatures they used were spot on.
If your getting too offended, something is wrong. I thought those X-Box pics of a guy with his "new X-Box controller" that turned out to be about 2ft wide were hilarious too.
Essentially, well known stereotypes or themes are being parodied here. Get over it.