Snow Falls - S1-E3
Visible crew/equipment: When the horse carriage is ambushed, just as Princess Abigail can be heard screaming "Please, help me", the camera pans downward and a horse wrangler wearing a blue baseball cap can be seen in the lower left hand corner, hiding behind one of the horses. (00:03:20)
Continuity mistake: When Hook comes to see Emma at the sheriff's station, his earring disappears when she kisses him goodbye.
Tallahassee - S2-E6
Continuity mistake: When Emma is arrested, she has a flower tattoo on her left wrist. When she's climbing the beanstalk with Hook, in a few shots, her wrist is bare, and you can see that the tattoo is missing; this happens, for example, when she remarks, "You should be used to people not trusting you." (00:09:10 - 00:29:30)
Tallahassee - S2-E6
Continuity mistake: In the giant's treasure room, there are many giant gold coins near the skeleton of Jack the Giant Killer. The amount and position of the coins repeatedly changes. For example, when they find the skeleton, there are several coins on the edge of a small dais, but when Emma saves Hook from the trip wire, they are missing. (00:24:40)
Continuity mistake: At Lake Nostos, when Emma is pinned down by Hook, the ground beneath her changes between shots, with regards to the markings in the sand (from the fight), as well as the amount of stones, twigs etc. (00:29:00)
Revealing mistake: When Sheriff Graham pulls in front of Emma in a police car, the big sign on the storefront behind Emma says "Storybrooke Coffee Co." However, as Graham gets out of the car, you can see a circular sign on the side of the building, which says "Steveston Coffee Co"; Steveston is the Canadian town which doubles as the backdrop for the town of Storybrooke on Once Upon a Time. (00:05:30)
The Thing You Love Most - S1-E2
Revealing mistake: When Emma walks Henry to school, as Emma says "Because I'm the daughter of Snow White and Prince Charming?", a reflection of the clock tower building is visible in the window behind her, only there's no clock (the top two layers of the clock tower, including the clock, are visual effects). (00:13:40)
Tougher Than the Rest - S6-E12
Visible crew/equipment: When Sir Henry searches for his mother and The Evil Queen along the water's edge, in the shot where he says, "They crossed the river", as he turns his horse around, a horse wrangler's hand can be seen holding the horse's bridle in the lower half of the screen, guiding the horse to turn around. (00:04:20)
The Miller's Daughter - S2-E16
Visible crew/equipment: When Rumpelstiltskin goes to Cora as she is trying on her wedding dress, as he sits down on the chair behind her, you can see the tape used to mark the spot on the floor - it's bright red and in an X shape. (00:24:39)
Continuity mistake: When Red meets Quinn, the way her hood is draped over his arm changes throughout the scene. The same thing happens when Red is holding it afterward. After Quinn drops the hood, the way the garment is crumpled up on the ground changes between shots. (00:12:05)
Continuity mistake: At Granny's, when Ruby is clearing tables and Billy startles her, the amount and position of the food on a plate changes between shots. The cup and the napkins also change position on the table. (00:02:35)
Continuity mistake: The dove that Mary Margaret finds in the woods has white feathers with a reddish plume around its neck. When she releases the bird after the storm has passed, it is not the same dove. The dove that she releases is completely powder white, with a different colored beak. (00:12:20 - 00:29:40)
The Heart of the Truest Believer - S3-E1
Continuity mistake: After Neal wakes up on the bier, after he says "A .45 caliber arrow", Aurora's dress keeps alternating between having straps and being strapless between shots. (00:13:25)
Continuity mistake: When Emma and Hook kiss, in the shots from behind Hook, Emma tilts her head to the right. In the shot from behind Emma, she tilts her head to the left. In addition, Emma's left hand jumps from the back of his head to his shoulder between shots. (00:37:10)
Continuity mistake: When Regina is on the stretcher, she has a yellow coat around her shoulders. As she pushes Sidney away, the coat has vanished into thin air. (00:23:50)
Continuity mistake: In Neverland, when Rumplestiltskin's father tells him to think of a food, a slice of cake appears in the palm of the boy's hand. When Rumple walks to place the cake down, suddenly there's a round, white doily under the slice, but when he sets the cake on the wood the doily is gone again. (00:16:50)
There's No Place Like Home - S3-E22
Continuity mistake: When Prince Charming shows Snow White the wanted poster, the poster does not have Snow White's name on it. Two shots later, he's still holding it up, but now the poster has her name printed on it. (00:05:30)
Continuity mistake: When Jefferson hands Emma the scissors, the sharp end is pointing towards Emma. However in the next shot the sharp end is pointing in the opposite direction. (00:24:35)
Tallahassee - S2-E6
Continuity mistake: When Hook and Emma find the skeleton of Jack the Giant Killer, in the close-up shot, Jack's sword is in the skeleton's hand. When Emma remarks, "With that toothpick?", the sword is lying beside the hand. When Emma grabs the sword while being chased by the giant, the sword is back in Jack's hand. In addition, the skeleton's arm alternates between being bent and sticking straight out between shots. (00:23:15)
Continuity mistake: When Henry lies on the bed, the position of his legs goes from one leg being crossed over the other, to being parallel to each other, between shots. (00:38:40)
Chosen answer: Even if one can see the future, it can be somewhat vague and left open to interpretation.
raywest ★
He can sees the future all jumbled up. It is like a puzzle, it is hard to put together, but even when he does put it together it is not set in stone the future can change.