In medium shots of the village that becomes Jack's civilization, a river can be seen running though the village, but it's not there in long shots.
After Jack leaves the two Shoalin warriors to fight the statues and goes after the portal why don't some of the dumb statues follow him.
How could those rock statues be able to stay on the wooden bridge without being too heavy to fall through?
Trivia: The stuffed doll looks a lot like Jack's "friend" from "Jack and the Creature."
When the Hermit stands on the glass dome just after dawn, his shadow lengthens as the sun rises.
Hermit/Aku's reflection on the water reveals his true form. But when Aku drank from the oasis as the warrior woman (in the episode of the same name), his image was unchanged.
During the fight between Jack and the time portal guardian, the collar on the time portal guardian's suit keeps disappearing and reappearing.
Trivia: This is the first episode where Young Jack speaks.
Trivia: Apparently, restraining orders still exist in this futuristic world.
As they were seated on top of the train, Jack's hat and Josephine's parasol should have created so much drag force from the speed of train that the items should have flown away.
When Jack punches the DJ in the face the DJ's gold tooth is white. In later scenes the same tooth is missing.
When the pacifier came out of his mouth, when he got surprised, how did it get back in?
When Caccitore starts eating the lasagna, Chicken Jack's legs briefly disappear.
Where did Jack keep his sword during the whole chicken ordeal?
The shoe salesman's shop is named "Foot-Chalet." However, when Jack drops down and lands in the broken glass, the hyphen in the sign disappears in one shot.
Trivia: Among the shoes Jack tries include a pair of spiked heels (which he realizes too late that they're actually a woman's shoes); cast-iron shoes (that prove to be too heavy for Jack to jump in); wooden shoes with a water-base complete with real goldfish (which break in about 3 seconds); a simple pair of tennis shoes (that get stolen from Jack by two street punks); extra-furry boots (that are revealed to be living creatures); and a pair of experimental tennis shoes that "pump up" and give Jack extra jumping power (although the pumping part pops and Jack goes flying).
As the enraged Demongo releases all of the warriors whose essence he holds and they swarm over the cliff to chase after Jack, the same warriors appear three times (in other words, the crew repeats the same frames at least thrice). Look for the green mantis-like creature on the left to verify this. It's not really a goof, just a common trick in animation (especially with background loops), but a little annoying nonetheless.
Phil LaMarr's name is mispelled Pill in the end credits.
Not a goof with-in the episode itself, but for some strange reason, this episode is known as "Jack versus The Five" even though there are only four hunters he has to contend with. Someone can't count.
When Jack enters the village, there's a man turning three pieces of meat on a pole. However, there's no fire underneath the meat.