Mr. Ping mentioned he raised Po for 20 years before Mr. Ping told him he was adopted and behind-the-scenes it's mentioned that Po is in his 20s, in Secrets of the Scroll Po was a teenager 10 years ago and in Kung Fu Panda 2 Shifu mentioned Po found inner peace at a such young age. However, in Kung Fu Panda 2 Shen waited 30 years to rule over Gongmen City alongside his cannon probably waited ever since then he started to use fireworks as an weapon, it's not even mentioned or shown that Shen began to use fireworks as a weapon years before or it was less than 30 years ago for the panda massacre and how could Shen's parents be concerned for about a long 10 years before they had to know Soothsayer's prophecy?
Shifu reffered ducks and not geese to them who commented and went past Po.
Po did not know what Chi was before Shifu shown and told him about it, but in Kung Fu Panda: Legends of Awesomeness he already knew what chi is.
Po still had his Tigress action figure, but in Secrets of the Scroll a rabbit kid got all of his Furious Five action figures Po later didn't need them anymore.
It showed that Po was miserable to roll and seemed he did it first time, but in Kung Fu Panda 2 he was already able to roll?
Um, I will just say I guess that as usual every franchise has some its problems no matter what. To me there's only three possible ways to try to get it all squared out. 1st you could just live with it, get advice of others, or try to figues it out for yourself. To me here's what I would say.
1. Shen was waiting to become emperor for a technical 30 years all together, 10 years, then another 20 after the massacre.
2. I don't consider Legends of awesomeness cannon due to it having *Too* many inconsistencies.
3. Po could've have made another set of Furious Five action figures (although not very likely but possible)
4. Po probably could, sorta roll inside KFP2, I mean as a kung fu master it would be important to learn different ways of dodgeing attacks. As for rolling down hills and be able to know where you're going, thats a differnt story.