During the last fight, Dre holds his right leg after injuring his left, then switches back to his left in the next shot.
Dre places his chopsticks on the left side of his food tray at the food court. But the next frame he has them in his right hand and placing them onto the food tray for the second time.
The newspaper clipping on the hood of Mr Han's now-beat-up car is covered with pieces of windshield. Dre picks it up, removing the glass. When the camera shows the clipping right after, the pieces of glass are back on the clipping.
When Dre watches the woman charming a cobra on the mountain, he first watches from behind a window with its bars all in place and parallel. Then he walks farther up the hall and peers out a second window that has one bar bent out of place, allowing him to peek his head farther out for a better view. He has his head out this second window when Han calls him, but in the next shot he's behind the first window again as he responds to the call.
In Mr. Han's office, he gives Dre a full glass of water. Cut to close up and Dre clearly tips up an empty glass.
During the celebration of winning the first rounds of the tournament, a photographer is seen taking pictures from very close range; under one meter. His camera is sporting a telephoto lens, which usually have a minimal macro distance of 1.2 to 1.4 meters. There is no way the photographer could have been taking clear pictures.
Though the plot of the movie revolves around kung fu rather than karate, the title "The Karate Kid" is a direct reference to the bullies calling him the "Karate Kid" when he takes up a stance at the beginning of the fight.
The plane shown taking off to take the Parkers to China is different from the one shown landing in China. The planes shown have different registration numbers which are seen on the fuselages (specifically B-2460 and B-2443). However there is no explicit statement that the plane we are looking at is "their" plane, just that it's an Air China plane taking off / landing.
In the backstreet fight scene, Mr. Han bonks two of the kids' heads together. You can clearly see that one is behind the other.
When Mr. Han and Dre visit Master Li's Kung Fu school, they witness him punishing one of his students by slapping him in the face. The student falls backwards as if being hit almost a full second before Master Li's hand would have connected with his face.
There is an obvious stunt double for Jaden Smith when he is holding onto different vehicles while he is on his skateboard going to Mr. Han's house for the first time.
When Dre first visits the Fighting Dragons studio, the count is in Japanese. Being that this is Kung Fu taught in China, the expectation would be that the count be in Chinese.
During the back street fight, Mr. Han knocks two of the bullies into a couple of short posts with large concrete bases. When the boys fell on them, the concrete block on the way is knocked over and is clearly a foam or cardboard prop.
The Qixi Festival that Dre attends with his mom and Mr. Han falls on the seventh day of the seventh month of the lunar calendar. Though the exact date in our modern calendar varies from year to year, it is usually sometime in August. However, a few scenes after this festival, Mr. Han says the date is June 8th. This is not possible unless 11 months had passed in those few scenes.
In the music competition scene, the boy playing Flight of the Bumblebee is heard playing high notes near the end of the music but is at the left (low) end of the keyboard with both hands.
When Dre turns on the TV, the introduction to SpongeBob SquarePants (1999) is on. However, the video is halfway through the introduction, but the audio is near the end of the Spongebob Squarepants theme.
On the way from Beijing Capital International Airport (northeast of Beijing) to the Parker's new house they drive past the CCTV Headquarters (6km east of the Forbidden City) and then past the Beijing National Stadium ("Bird's Nest", 9km north of the Forbidden City). No one would drive this route.