At the end of the movie, Shifu spilled tea on the ground when he found out that Po decided to choose Zhen to be the next Dragon Warrior. But when Shifu walked away, the puddle of tea disappeared.
In one scene Po removes cover and put aside to enter a tunnel, but later when he is entering, the cover was not seen where he put it.
When the artifacts flew into the air, Po grabbed them with his arms, and he grabbed the scroll with his mouth. But when he was watching Zhen try to break the Urn Of Whispering Warriors, the scroll was still in his mouth, but the other artifacts were no longer in his arms.
In the 1st movie, Tai Lung didn't know that Po was a panda when he found out that he became the Dragon Warrior. But in this movie, he called Po a puffy panda when he was talking to The Chameleon. By saying that, he knew what Po's animal species was.
Despite the fact that he was erased from existence in the 3rd movie, Kai was summoned by The Chameleon.
In the Kung Fu Panda TV shows, Kung Fu Panda: The Paws Of Destiny and Kung Fu Panda: The Dragon Knight, people acknowledged Po's title as the Dragon Master. But in this movie, which takes place after the events of the aforementioned TV shows, they acknowledged Po's title as the Dragon Warrior, just like in the previous movies.
When Zhen tried to break the Urn Of Whispering Warriors, Po told her that he broke it twice. But in the 1st movie, he broke it once. And then, his biological father, Li Shan, broke it in Kung Fu Panda 3. Also, Po broke it in Kung Fu Panda: Legends Of Awesomeness, and it happened 3 times.
For some reason, Mr. Ping and Li Shan didn't see the Wanted posters of Po when they were searching for him.
The Chameleon was rejected by every Kung Fu school because of her small size. That was misleading because Mantis and Master Chicken became Kung Fu masters, and they were smaller than her.
In the 1st Kung Fu Panda movie, Po and Tai Lung were the same height. But in this movie, Tai Lung was taller than Po.
When The Chameleon shape-shifted into Tai Lung for the 1st time, her eyes were gold. But when she shape-shifted into him for the 2nd time, her eyes were blue.
When Tai Lung met Po in the 1st movie, he didn't know who he was, even though he heard Monkey say his name once. But in this movie, he referred to Po by his name when he was talking to The Chameleon.