Continuity mistake: At the end of the movie when Cheyenne is shaving, while Harmonica and Frank are having their shoot-out, he cuts himself at the sound of the gunshots. When Jill tells him that he is a handsome man the cut is gone. (02:22:25)
Continuity mistake: During the last flashback that reveals Harmonica's issue with Frank and the significance of the harmonica, the harmonica in the boy's mouth is sometimes dented, sometimes not. (02:22:00)
Other mistake: When Jill tries to leave Sweetwater in the morning after Cheyenne's visit, she runs into Harmonica. He has a very nasty, coarsely stitched injury in his cheek that is not accounted for, and for which there was no time to be received, stitched, and the stitches removed again. (Special Edition DVD has a deleted scene in which Harmonica is beaten up, which explains the injury, but it is a continuity mistake within the regular movie.) (01:12:25)
Revealing mistake: Jack Elam gets bothered by a fly crawling over his face (nice stunt, actually). When the fly moves over the bench, just before he catches it with the muzzle of his gun, look at the hind legs. You'll notice that the fly is dead. (00:07:50)
Other mistake: In the scene in Morton's Special Waggon where Wobbles gets pinned by Frank ("A man who can't trust his own pants") Harmonica lies on the roof, not so unseen as he hopes to be. When the train leaves Flagstone Station you see a shot of Flagstone on the track's right. But on the left you see some far more modern housing. That is when see along the top of the train over Harmonica. (01:19:10)
Revealing mistake: When Jill get's off the cart at the post station look how the light falls on the cart with the luggage and the rock in the background. It obviously comes from opposite directions. (00:31:05)
Factual error: It seems unlikely that the bullet hole in Harmonica's jacket should have burned edges - he was shot at a distance of more than ten metres. (00:36:35)
Factual error: When Harmonica climbs down the ladder, only to meet Frank at the other end of a '45, we see that the ladder is electro-welded to the wagon and the steps are also electro-welded to the legs of the ladder - rather lousy welding seams, too! The movie takes place around 1870. Electro-welding started during the '90s, but the method got practicable only in the 1920s - and began to be commonly used in the late '30s when the great navies (except for the Royal Navy) started to use the method for their first-line ships. The great leap forward came during WW2, when Liberty ships and many other vessels were electro-welded. (01:19:50)
Continuity mistake: The bullet hole in Harmonica's jacket changes size, shape, and degree of bloodiness during the scene at the post station. (00:36:35 - 00:42:45)
Continuity mistake: During the shoot-out between Harmonica and Frank lengths and directions of both opponents' shadows keep changing, e.g. when Frank drops his jacket. (02:17:40)
Continuity mistake: After Jill's arrival at the train station she leaves by cart. The way the luggage is piled on back changes totally when they go through Monument Valley. There are reasons to believe that it's a different cart as also the horses seem to change (check the mane which changes colors and sometimes falls to the left, sometimes to the right). (00:29:00)
Continuity mistake: In the scene where Cheyenne shoots a man through his boot the curtains at the top the window are happily moving in the wind, but when we see them from outside they are almost still. (01:28:50)
Continuity mistake: When Harmonica shows up at Sweetwater, the bullet hole in his jacket that he received at the station is gone (gone, not mended.). (01:13:00)
Revealing mistake: In the morning after Cheyenne's visit Jill attempts to leave Sweetwater for the second time. She carries a lot of luggage to the stable, and it's very obvious that it's all empty. (01:11:30)
Continuity mistake: On the way to Sweetwater the cart goes through Monument Valley. There, the very long shadows of the cart and the rocks don't match the time Jill has left the station (some time after 10). A bit later, when they pass the construction site, the shadows are short and more fitting for the time of the day again. (00:29:00)
Audio problem: In the last shot of the shoot-out scene at the station, we see Harmonica's carrier bag in the extreme foreground, and windmill in the extreme background. The windmill has stopped, but you still hear the wind blowing, and a few seconds before you have heard the squeaking pump. (00:13:50)
Revealing mistake: When Jill offers herself to Cheyenne she puts down the kettle on the table so hard that the lid falls off. If you look closely (slow motion helps) you see the lid dangling by the knob between her fingers before she puts the kettle down. (01:03:10)
Continuity mistake: The whole scene in the post station takes about 12 minutes. During this time the bartender finishes his cigar almost completely, a task that takes at least 45 minutes if you smoke fast. In the very last shot the cigar is again much longer but half hidden in the hand, apparently to make it look shorter. (00:32:20 - 00:44:00)
Factual error: At the end of the post station scene Cheyenne advises Harmonica to "watch those false notes". Harmonica anwers this with a discordant chord that could not be produced on a harmonica like his. (00:43:35)
Continuity mistake: When Jill attempts to leave Sweetwater for the first time her hair is combed out of her forehead, enhancing its striking beauty. When she opens the door, only to face Cheyenne and his men, the wind blows her hair even further back, but when the camera cuts to outside the wind is coming from behind, blowing her hair over her face. (00:57:50)
Answer: 1) Jill is a prostitute from New Orleans. She seeks out a new life out West. Love is irrelevant here. 2) She was promised a country living, a family, and wealth. That's why she is looking not only for money or gold but also for the reason her family was killed. 3) So Leone can show her beautiful body. 4) She's saving her life. She's a prostitute and I guess she knows how to fake it. Remember: "There's nothing that can't washed off by a hot bath".