These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
What finally stuns Lord Shen at the end is notPo countering cannonfire with kung fu to singlehandedly destroy his fleet, but the fact that Po is neither permanently mired in a Heroic BSOD believing the lie that his parents abandoning him because they hated him, nor charging in a Roaring Rampage of Revenge for the extermination of his people.
When Po discovers what Lord Shen did to his parents, and for that matter species, his response is to...let go of his pain and find inner peace. Shen, who has never got over his own deep-rooted issues, is utterly shocked.
Played with when the Soothsayer and Shen first meet Po. They know that Shen attempted genocide against the Pandas, and assume that the reason that the Panda is here is to a) avenge his family/species, and b) destroy Shen once and for all. Both are shocked when they learn that not only had Po never heard of Lord Shen, but had no idea why he should have. The look on Shen's face when Po just brushes him off, totally ignoring the well-prepared speech upon their first meeting, is priceless.
Po's nightmare in the boat before the team's arrival in Gongmen. He reunites with his parents, only to find that they've replaced him with a radish which is quieter and better at kung fu than him. Said radish then proceeds to kick his ass.This sounds like a straight up version but it is less BLAM then it appears. Po is wrestling with issues of identity, where he came from, and his origins. The fear that his parents gave him up because they were trying to replace him or that they simply didn't want him is a very real fear of some adopted people, and his mind shows this quite clearly. He wishes to know why his parents gave him up, and why they wouldn't come back for him. The radish, though, was entirely BLAM, but it was a dream. The brain uses dreams to sort out bits and pieces of information that it gathers during waking hours, and since radishes played a large role in his father's tale, it's understandable that it would make it into the dream. Kung Fu is also a massive part of his life, so it would be incorporated in as well...
While trying to convince Masters Ox and Croc to escape the prison, Po delivers a Rousing Speech about how they will defeat Shen and destroy his weapon. A random prisoner then enthusiastically agrees, but he's never seen again. Oddly, he was a boar and had a completely unique character model.
Foe Yay: Sure, he was talking about his cannons, but there was just something about the way Lord Shen stroked Tigress' face with the tip of his wing, whispering, "Beautiful..." that invoked this in so many creepy droves.
Boss Wolf mentioning how "Cuddly" Po is on a few occasions.
Oddly enough, there's a Shen/Viper pairing out there. While there's little "proof" in the film, fans have paired them up.
Germans Love David Hasselhoff: For all the good reviews and the high Cinemascore audience grade of the film, the film unfairly underperformed at the box office in North America although the domestic gross it earned did more than pay for the production budget. However, internationally, especially in China, the film became the #1 animated feature film worldwide of 2011.
Moral Event Horizon: Lord Shen starts the movie far on the other side of this trope. He overheard a prophecy that a panda would be the warrior to stop his plans to conquer China. His solution? Order the genocide of all the pandas. And he was proud of doing it!
Narm: Po's "IIII loooove yoooou guyyys" line during the final battle can come off more Tastes Like Diabetes than a Heartwarming Moment. Though it's arguable whether or not this line was meant to be taken seriously in the first place.