Revealing mistake: When Emma opens the door of Any Given Sundae in the 2011 flashback, you can see the backdrop curtain used to insert the Storybrooke main street, thanks to its shadow in the middle of the road and a few folds reflecting the light.
Continuity mistake: The flashback scene where The Snow Queen takes Emma's video camera away from Kevin differs from what is seen on the video recording of that moment in "Breaking Glass" and "Family Business." For example, in the recording, Ingrid says, "We respect property in this house, Emma." In the actual scene, she says, "We respect property in this household, don't we, Kevin?"
Unforgiven - S4-E13
Revealing mistake: When Snow White and Prince Charming arrive home at the Royal Castle on horseback, you can easily see that the ones riding are not Ginnifer Goodwin and Josh Dallas, but their stunt doubles. (00:02:55)
Revealing mistake: When Regina is waiting outside the Storybrooke Library, there is a wide shot of Cruella's car making its way down the road. On the building on the right side, you can see a large vertical sign on the side of the building, which lists several local businesses. If you read the top of the sign, you can see that it says "Steveston Hotel." Steveston is the Canadian town which doubles as the town of Storybrooke on Once Upon a Time. (00:20:45)
Revealing mistake: In real life, the Storybrooke Cannery is known as the Gulf of Georgia Cannery, a real cannery in Steveston village, the town which doubles as the town of Storybrooke on Once Upon a Time. In most episodes where the cannery appears, the name on the building is replaced with the Once Upon a Time version. However, in this episode, when Emma is driving in her father's truck following shortly behind Cruella's car, there is a wide shot of Cruella's car turning right, and you can see the sign on the cannery, which has not been updated properly: Bizarrely, the first word of the real business name is still on the building, and the first three letters of the fictional name are missing, making the name on the building "Gulfrybrooke Cannery." (00:23:20)
Revealing mistake: After Mr. Gold's group leaves Mary Margaret's apartment, in the wide-shot where Mr. Gold asks Cruella and Maleficent to follow Regina, a direction sign pointing to a shop called "Steveston General Store" can be seen on a building. Steveston is the Canadian town which doubles as the town of Storybrooke on Once Upon a Time. (00:14:30)
Revealing mistake: When Snow White and Prince Charming hurriedly make their way through the woods in the beginning of the episode, in the shot where Snow White jumps over a log, you can see the face of Ginnifer Goodwin's and Josh Dallas' stunt doubles. Josh Dallas' stunt double can also be seen as Snow and Charming are running thought the woods in the previous shot.
Revealing mistake: During the car chase scene, when Lily is driving Emma's car, there are several wide shots of the car driving down the road and you can see that the one driving is not Agnes Bruckner, but her stunt double. Lana Parilla's stunt double can also be seen in several wide shots when Emma and Regina catch up with Lily and try to overtake her. (00:30:55)
Revealing mistake: In the first shot of the scene where Emma and the others arrive in Storybrooke in their cars, on the left side of the screen, you can see a sign behind a branch. It says "Steveston Museum and Visitor Centre." Steveston is the name of Canadian town which doubles as the town of Storybrooke on Once Upon a Time. (00:07:00)
Continuity mistake: When Mary Margaret gets thrown by the Lily dragon into a rock, her blood smear on her head is large and messy. They cut away and cut back to her quickly and it is nice and neat with two blood drop lines slowly forming away from the cut. (00:44:00)
Continuity mistake: When we see Emma giving Merida back her heart, shoving her away in the same motion, a couple of shots later the camera turns on Emma and we are shown her still doing the same movement, although several seconds have passed. (00:33:40)
Revealing mistake: When Hook tries to rip Zelena's heart out, as a blast of magic hurls him into the wall, you can see that the one who actually hits the wall is Colin O'Donughue's stunt double.
Factual error: The episode opens with Emma going to the State Theater in Mpls. in 1989. The theater was closed for renovation at that time, and hadn't shown a movie since 1975. It was the Jesus People church all through the 80's.
Plot hole: To wake Mr. Gold/Rumplestiltskin from his coma, Emma needs an object that touched him before he became the Dark One. Hook shows her a sword, telling her how he held it to Rumplestiltskin's head and taunted him. However, the sword that Hook shows to Emma, is not the sword that he threatened Rumplestiltskin with in "The Crocodile." The sword that he used to threaten him had a unique, golden handle. When Hook and Rumplestiltskin met again a few years later, Rumplestiltskin took the same sword from Hook and dueled him with it. When Rumplestiltskin vanished into thin air after cutting off Hook's hand, he took the sword with him. The sword that Hook shows to Emma, which Emma uses to wake Mr. Gold, has a black handle with a completely different design, and is the sword Hook carried after the other one was taken from him; he can be seen using it in episodes like "Queen of Hearts", "Lost Girl" and "The Jolly Roger." This means that the sword Emma uses to wake Mr. Gold from his coma never actually touched him at all; however, the spell still works.
Other mistake: When Belle and Gold run from Merida in Gold's shop, she shoots an arrow through the door. We see the end of the arrow (with the white feathers) sticking out of the other side of the door. When when Merida pushes the doors open, the end of the arrow is missing, even though the arrowhead end is still sticking out.
Continuity mistake: When Killian Jones, a.k.a. Captain Hook, is talking to Emma on the street, he points to one of his rings and reveals that it belonged to a man who insulted him by calling him "One Hand Jones." According to Hook, he killed the man in front of his wife, and took his ring as a trophy. However, as seen in 2-04 "The Crocodile", Hook was already wearing this ring before he lost his hand to Rumplestiltskin. This is best seen while he and Milah are drinking and gambling at the tavern: In the shot of the dice landing on the table, you can see Hook's hand resting on the table, wearing the same ring.
Revealing mistake: As Hook is chasing King Arthur through the woods, there is a shot of Arthur running, where you can see that the one running is not Liam Garrigan, but his stunt double. In the next shot, Hook is hot on Arthur's heels and you can see that it is Colin O'Donughue's stunt double who is chasing him.
Continuity mistake: When King Fergus signs the witch's contract by stamping the hot wax with his ring, the seal is placed right on top of one of the last word of the final paragraph. When the witch shows Merida the contract two years later, the seal has moved several centimeters below the contract. There are also subtle differences in the witch's handwriting. (00:04:45 - 00:06:45)
Revealing mistake: When Hook and Mr. Gold are dueling aboard The Jolly Roger, in several shots, you can see that the ones fighting are not Colin O'Donogue and Robert Carlyle, but their stunt doubles. (00:28:25)
Continuity mistake: When Mary Margaret and Henry are being teleported out of Granny's Diner by Nimue, they aren't wearing any outdoor clothing. However, when they emerge at the pond with the others, Henry is wearing a jacket, and Mary Margaret wears a coat and a scarf.
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.