Continuity mistake: Emma has a flower tattoo on her left wrist. Throughout the series, there are subtle changes in its design, and its position on her arm. For example, when Emma is sitting at the table with Mary Margaret in "The Thing You Love Most", the tattoo has six petals, and is located about an inch below her hand. When she's on the phone with Ruby in "Red-Handed", the tattoo is much bigger, and the petals are arranged differently; it has also moved further up her arm, and is almost touching her hand. When she's arrested in "Tallahassee", there are five petals instead of six, the petals have a rounder shape (in "Red-Handed", they were rather pointy), and the tip of one of the petals is touching her hand. When she pulls her hair behind her ears at the tavern in "Snow Drifts", said petal is thinner, and is no longer touching her hand. When she touches Hook's face in the diner in "Birth", the tattoo has moved about a centimeter down her wrist, and the petals have a brownish color, but in previous episodes, the petals have no color. When she touches Hook's face in the Middlemist Field in the next scene, the color is gone.
Continuity mistake: The exterior shots of the buildings located across the street from Granny's Diner do not match the view seen through the front door, from inside the diner. The most obvious example is the building next to Storybrooke Country Bread, on the opposite side of the street. In the exterior shots, on the left side of the bakery, there is a blue wooden building (this can be seen, for example, when Emma is walking Henry to school in "The Thing You Love Most"), with a huge gap of approximately ten meters between the two buildings. In the interior shots where the front door of Granny's Diner is open, the view is drastically different looking: For example, when Regina enters the diner to confront Mary Margaret in "The Shepherd", when Emma brings Henry to the diner in "Welcome to Storybrooke", when Zelena enters the diner in "It's Not Easy Being Green" and when Emma comes into Granny's Diner to ask Hook out in "The Apprentice", the characters open the front door, and now there is a completely different building next to Storybrooke Country Bread. The new building seen through the doorway is made of bricks and has a completely different color, and there is no longer any gap between the two buildings; they are touching each other. Also, in some episodes, like "The Shepherd" and "7:15 AM", in the scenes inside the diner, you can see a grey wall on top of Storybrooke Country Bread. In exterior shots, there is no such wall.
Continuity mistake: The blade on the Dark One's Dagger has one side with the name of the Dark One inscribed, while the other side is decorated with a pattern. Throughout the first four seasons, the name keeps switching from one side of the blade to the other. In some scenes, the writing is right side up when the dagger is held in the left hand and facing the wielder: This happens, for example, when Rumplestiltskin finds the dagger in "Desperate Souls", when Mr. Gold gives the knife to August in "The Return", when Gold summons the wraith in "Broken", when Cora has the dagger in "The Miller's Daughter", when Zelena controls Mr. Gold in "The Tower", when Gold triumphantly shows the dagger to Zelena in "Kansas" and when Belle controls Hook with the dagger in "Heroes and Villains." In other scenes, the characters are right side up when the dagger is facing the wielder and held in the right hand: For example, when Rumplestiltskin summons Zoso in "Desperate Souls", when Cora steals the knife in "The Queen Is Dead", when Gold uses the dagger in "Going Home", when Regina picks it up in "Kansas", when Gold hides the dagger in "Snow Drifts" and when Gold opens the sorcerer's hat box in "A Tale of Two Sisters."
Continuity mistake: The headstones and statues around Regina's heart vault change dramatically throughout the series. For example, when Emma and Graham find the vault in "The Heart Is a Lonely Hunter", there are two headstones on the left hand side of the vault, which are parallel to the side of the vault, and a statue of a woman on the right hand side. When Mary Margaret and David are standing outside the vault in "The Queen is Dead", there are two completely different headstones on the left hand side, which are perpendicular to the side of the vault. There is also a cross-shaped headstone there, which wasn't there before, and an angel statue, which appeared on the left hand side of the vault when Regina went there in "The Doctor", is gone. When Regina is inside the vault with Mr. Gold in "Welcome to Storybrooke", in the establishing shot, two headstones with a cross engraved on them can be seen near the vault, but these headstones were not there in previous episodes. When Regina goes to the heart vault with a disguised Peter Pan in "The New Neverland", the statues are gone, and there are hardly any headstones around the vault at all. When Emma leaves the vault in "Breaking Glass", the statue on the right reappears, but there are no headstones in front of the vault; however, when Regina is locked inside the vault in "Shattered Sight", there are several headstones in front of it, and the angel statue on the left is back.
Continuity mistake: The location of Regina's heart vault changes throughout the series. For example, when Emma and Graham find the vault in "The Heart of the Lonely Hunter", when Regina and a disguised Peter Pan go to the vault in "The New Neverland", and when Regina hides Zelena's pendant in "Kansas", there is a slope on the left hand side of the building, but when Mary Margaret and David are standing at Johanna's grave in "The Queen Is Dead", when the green smoke goes out of the vault in "Kansas", when Regina is inside the vault with Henry in "The Apprentice", and when Regina is trapped inside the vault in "Shattered Sight", the terrain on the left hand side is flat. The trees around the vault also differ between these scenes.