Lighthouse - S6-E5
Revealing mistake: 6-05 - The Lighthouse: While Sawyer and Locke are climbing down the ladder, Sawyer's stunt is noticeable because his shirt's colour is different, his hair is darker, and the sweat stains on his shirt disappear.
Continuity mistake: Season 6, episode 7 "Dr. Linus": When Ben writes 'ELBA' on the blackboard, he underlines it with a curved line, but as he walks to the back of the classroom in the next shot, you can see over his shoulder that the line is now straight. The handwriting of the letters has also changed noticeably.
The End (1) - S6-E17
Revealing mistake: When Desmond moves the rock, Smoke-Locke and Jack fight outside the cave while an earthquake shatters everything. Watch the leaves around and you'll notice that they don't move at all, giving away the camera effect. This also happens later on when Hugo, Ben and Jack are about to fix the cave of light.
Continuity mistake: After the submarine sinks, Jack lays Sawyer on the sand. In the last angle his head swaps from facing sideways to up.
Continuity mistake: Season 6 Episode 3 "What Kate Does". When Sawyer is about to leave the temple he is holding a SIG pistol. When he opens the door and raises the gun again it has changed into a Glock.
Continuity mistake: 6-01-02 - LAX: Before Hurley grabs a gun, while Sayid is lying down, his head position keeps swapping from straight in the close-ups to tilted to the right in the wide angle.
Continuity mistake: Lost 6-01-02 - LAX: When Sawyer rescues Juliet, her hand moves next to her face. Half a second later it's away.
The End (2) - S6-E18
Continuity mistake: As Locke stabs Jack's neck in their final battle, the wound is visible, above the neck line of his shirt. Once the rain stops and Jack speaks of his plan and kisses Kate, the wound is missing for the entire scene. The wound reappears on his neck during Jack's scene with Hurley and Ben at the cave opening. During the final sequence as Jack lies down and closes his eyes, the wound is visible in most shots, but in the final two wide shots, the dry blood make-up appears to be coming off and once again there is no neck wound.
Continuity mistake: 6-01-02 - LAX: When Sayid is drownd and laid on a carpet, his head swaps from being by the edge of it almost out, to several inches inside the carpet.
Ab Aeterno - S6-E9
Factual error: Season 6, episode 9 "Ab Aeterno": The episode is supposed to take place in the Canary Islands, Spain. However all the characters speak with either Mexican, Puerto Rican, or Cuban accents. In the 19th century there wasn't such a blend of American cultures.
Continuity mistake: When they are approaching the plane, Sawyer is in the front and it appears as if Sayid grabs Claire's hand. In the next shot Sawyer is next to Sayid and Claire. (00:15:55)
Continuity mistake: When Jack and Claire open the music box, from the back angles their heads are almost touching each other, but from the front angles it's noticeable that both guys are sitting wider apart.
Continuity mistake: After the submarine sinks, Jack is in the beach hugging Kate and a strand of wet hair is on his forehead. When the angle changes the hairstyle has changed and his forehead appears clear.
Continuity mistake: When the Smoke smashes the armed guard against the cage he lies unconscious with his left arm stretched out. A frame later, from another angle, the arm rests by his side.
The End (1) - S6-E17
Audio problem: When Desmond, Locke and Jack are standing outside the cave with light, Desmond says "maybe I can find a way out for you too," or something like that. Jack replies, "there are no do-overs." The camera then goes to over Jack's right shoulder as he says, "I tried that once." However, the words don't match what his mouth is saying.
Continuity mistake: Season 6, episode 8 "The Package": When Charles Widmore hands Jin the camera and tells him to turn it on, the lens is already out, therefore the camera is already on. When the shot cuts away you can hear him turning the camera on and the motor extending the lens.
Continuity mistake: When we first see young Jacob holding the white stone with his brother, the stone he has changes shape from long and rectangular to square.
Ab Aeterno - S6-E9
Continuity mistake: Season 6, episode 9 "Ab Aeterno": When Jacob pulls Richard upright after dunking him, his hair flies back over his head, leaving his face fully visible. The shot changes to a front view and Richard's hair is now covering most of his face.
Answer: Using a mold, a realistic pregnancy belly is made of latex (rubber), including the distinct belly button, to suit the proportions of Emilie de Ravin who plays Claire. It is then painted with a special paint/adhesive compound that adheres to the surface and for shots of the actual belly, additional veining and stretch marks are airbrushed on.