When I beat the Castle, the cutscene afterwards made it seem that a new stage opened on K. Rool's ship. But I went there and, apparently, there was no new stage. So, I wasn't sure what to do. I thought that, perhaps, I had to have all the blue prints to open the stage, so I went back to the Aztec stage to attempt to clear it out. I was able to find some stuff (Lanky's blue print, and every kong now has that stage's banana medal), but I missed others (I still couldn't find Diddy's blue print). I eventually decided I had exhausted exploring that stage, at least for now, so I went back out into the "hub" world... and found another stage, almost in plain sight! I probably was supposed to find it earlier; the gold banana requirement for getting in was less than for the Castle (this new stage only required about 60 gold bananas, and I have over 120).
I LOOOOOOVE Flying Omelette!!
Crawl and 1000