Other mistake: After Pinball douses "Cochise" with flammable liquid, the match he throws extinguishes before it leaves his hand. (00:22:45)
Other mistake: When the plane is at Carson City for exchange of prisoners, the guards have jackets with 'Dept of Prisons' printed on the back, but there is a bus with 'Bureau of Prisons' written on the side. (00:35:50)
Other mistake: Mykelti Williamson, who plays Baby-O, is listed in the beginning credits as Myelti Williamson.
Answer: If there was ever an emergency landing the weapons would be needed with the prisoners as they most likely will have to exit the plane at some point. There doesn't seem to be any information around that says that every prisoner transport plane would have the same amount of weapons or in the same spot but it seems likely most would have backup weapons for situations like that.
Lummie ★