Continuity mistake: When the Paper trader dies, he falls on the netting, with his hand on the tri-hull support. When the Mariner kicks the body overboard, it is lying completely on the support.
Continuity mistake: After Deacon is done showing the crowd the girl's tattoo, he turns to face the crowd and puts his bottle in his left hand, which is also holding his cigarette. When the camera angle changes, the bottle is now in his right hand.
Continuity mistake: Near the end one of the balloon's ropes is shot, causing the girl to fall in the water. Yet, seconds later as they float off all 6 ropes are holding the basket up, uncut.
Continuity mistake: When the Deacon begins his speech near the end of the movie, he is holding a bottle of liquor that is almost empty. Half way through the speech, the bottle is half full. Then when the girl is brought out, the bottle is now almost completely full.
Continuity mistake: As the Mariner readies to shoot the line off the Sky Boat, he has his knife in his mouth. After he falls in the water, it's suddenly back in its scabbard.
Continuity mistake: After the plane starts circling the boat, Helen prepares the harpoon gun. The barb on it is about four inches long, and is tilted about 45 degrees to the left (from the Helen's view). When the shot cuts to the circling plane, the barb is now straight up.
Continuity mistake: When nearing the trading post, the Mariner spots some globs of oil. When he goes to put his hand down to catch some, there isn't anything in the water, but his hand comes up oily.
Continuity mistake: When the Mariner escapes the Smokers for the first time, we get a wide shot of him at the helm. During the first shot, the boom is nearly straight over the boat and the outhaul is tensioned. In the shot afterwards, the boom is much further outward, and the outhaul now has lots of slack.
Revealing mistake: After the Mariner has Enola, the Deacon and his goons collide. In slow motion, the three of them are exploding a split second before the collision, and they're several feet from each other.
Continuity mistake: When Helen first pulls the Mariner up in the cage, his face is covered by the recycling goo, with lumps all over his face. After the cut to Helen for her line, his face is wet, but clean.
Continuity mistake: As the first skiers are being towed by the Sky Boat, two head for the left ramp, two go to the right. When the angle reverses to see them going up, all four appear to be going up the same ramp.
Answer: Most likely to make sure that the Mariner and Helen couldn't follow them and rescue Enola. They were trying to find Dryland and if Enola was taken from them, they'd never be able to find it. Also the smokers ship was filled with people and using the Mariner's boat and constantly going back and forth from Dryland to the ship would have taken too long. Better to use the ship they're all on and get them there quicker. Also, none of the Smokers could read the map that was on Enola's back.