During the final shootout, the gun Joe is using switches between a Glock and a Sig Saur between shots.
When Joe and Fon are walking in the park and Joe gets mugged, both the muggers and Joe are behind Fon, yet after she turns around and Joe and Fon have the emotional, wordless exchange one dead mugger is in front of Fon.
Joe shoots two men while his girlfriend isn't looking at him. Blood splatters all over his girlfriends back. The next shot of her back has hardly any blood at all.
When Joe blows Surat's aide by a grenade in the climax scene, we see the body of the man splits in two. Next shot is of the room door exploding due to the grenade blast. Then again we see the man's body splitting in half. The torso flies off over Joe and the limb portion remains in front of him. In the next shot both the torso and limb parts disappear and Joe goes inside the room.
When Joe is sighting the Thai politician through his rifle scope, the reticle changes from a varmint reticle with two horizontal crosshairs and a ladder sight for elevation and windage in the bottom of the picture, to a standard Duplex crosshair with windage and elevation marker lines.
The airliner in the 8th minute bears no tail number nor airline name.
In the river chase and shootout, it is unbelievable that an experienced assassin and gunman would miss the victim he is chasing in a boat, hitting the boat numerous times, some four feet below his target.
When Nicolas Cage's character opens the envelope containing information for his 3rd target, Damnoen Saduak, it lists his target's height as 178 and his weight as 74.
The scene following the one where Nicolas Cage leaves the building after he was caught during his last target, shows the crowd running off in panic. The face of one man in that crowd is blurred.
When Joe injects the needle with heroin into the arm of his helper in the beginning of the movie you can see the base of the syringe move, which wouldn't be possible if there was a needle attached to the syringe and in his arm. It's also a rather obviously prosthetic vein he's injecting into - the skin on the helper's arm is wrinkled for a couple of inches ahead of where the needle goes in, and it's also possible to see where the edges of the prosthetic are adhered to the actor's real skin.
When Joe arrives in Bangkok and he shows the customs agent his fake Canadian passport, his name at the top is Cadillac Vincent with two "L"'s, but at the bottom of the passport it is spelled Cadilac Vincent with just one "L".
When Joe makes the third kill a number of bullets are fired through the bottom of the boat yet it doesn't take on any water on or start to sink
In front of Joe's first executed victim is what looks like a 'wanted' poster. The title, 'wrazda,' translate in Polish as 'will give.'
Joe twice declares that he lives by the rules, leave no traces. Yet throughout the movie, he handles his guns and ammo with bare hands - leaving fingerprints and DNA all over them.
According to some websites, in Thai when men say Thank you, it should be Kob Khun Krap and when women say it, should be Kob Khun Ka. In this film however, both Cage and Yamnarm's character's use Kob Khun Ka.
During the scene that Joe kills Surat's gang members which was sent to kill him. When Joe goes down from the stairs, he asks the injured gangster about where is Kong. He said in Thai "Yoo Nai Kong". However, in Thai grammar, subject should place before verb. So, he should say "Kong yoo nai" instead.