* In the end of the Bog arc, [[spoiler: how does Kaiji manage to push all the balls into the hole with air coming out of it? Since the balls fall onto the plate, wouldn't there just be so many balls around the air streaming hole that eventually balls coming in would just fall on top of the huge pile of balls?]]
** Keep in mind, [[spoiler:the whole floor was actually tilted. It's possible that the air streams couldn't push the oncoming balls strong enough, therefore the nearest ones were able to fall into it from the inner part of the bowl (which we must assume was higher than the side of the winning hole), and the few other balls which entered it were probably aided by the fact that the air streams were blocked off for a few moments.]]

* At the end of the Chinchirorin arc, [[spoiler: after Kaiji has finally got the loaded dice in his hands, why does he think it's a good idea to just hand them over to a complete stranger? What if that guy was another accomplice?]]

* Why can't Kaiji just go to college? He gets 20 million yen, more than enough to pay both his and Ishida's debts, and still walk away with roughly 4 million yen. Just enough to go to college and get a degree. Easy poverty escape, yet he feels the need to gamble four of his fingers and all his money to get 100 million yen. Another baffling thing to me is that he references his "hospital bills." Healthcare is free, in Japan. You could argue that everyone pays for it with taxes, but might this Troper remind you that all the money he's getting from these gambles is tax free- gambling is illegal in Japan. So why can't he get his fresh start with the 20 million from E-Card?
** In 1995, at the time of the Human Derby arc, 1 USD generally averaged a 1:100 exchange rate. If Kaiji paid both his and Ishida's debts as promised, sure he'd have roughly 4 million yen, but that would only translate to about $40,000, which might be enough to pay for education, but that's assuming that Kaiji could even pass the exam to enter any school and also cover his living expenses given how preparing to take exams would take away from the time he can spend working for 900 yen per hour at that point. As for the hospital bills, that's an oversimplistic view of the Japanese healthcare system. They have a mixed system where they have the public hospitals paid for by taxes, and private doctors (think like the Kurosaki family in Bleach), with the main difference generally being cost versus speed, unless you need prohibitively expensive or controlled equipment for treatment. That's assuming that Kaiji could go to a legitimate medical professional though. It's mentioned that Kaiji needed an underground doctor to reattach his ear and fingers, most likely due to the circumstances in which they were severed. Certain types, quantities, and degrees of injury often result in the authorities being involved due to the possibility that the patient was the victim of a crime, or involved in illegal activity. Teiai is a legitimate corporation, but they do have to keep up appearances, so they can't just bring Kaiji to an ordinary hospital in his state. Fortunately, a business with as many shady connections as they do would know several mob doctors or other under the table medical professionals, resulting in them taking Kaiji to one of their people and putting the bill on his tab.

* In One Poker, [[spoiler: Kazuya says that a player is not forced to continue using a red life after betting it and winning back normal lives. Why then are both Kazuya and Kaiji able to raise in a way that forces the other player to use a red life or fold?]]