Continuity mistake: On 8/18/05, Noah protests Sam's offer to set up the garage apartment for him. He says that he'll just use his old room. But Noah wouldn't have an "old room" in this house, as the house he grew up in was sucked through a portal into Hell while he was away at college.
Continuity mistake: On 5/31/05, Martin refers to having been with Katherine for "more than twenty years." But he's only been with Katherine since they left Harmony together, which happened after the birth of Martin's youngest daughter Paloma. And Paloma graduated from high school about a year earlier, so she's not quite twenty herself, meaning Martin and Katherine have been together for at most nineteen years.
Continuity mistake: When Eve arrived home from LA on 11/28/03, she had changed her clothes since the last time she'd been seen. But Eve and TC weren't shown with luggage at any point in time; they went to LA on the spur of the moment to help Whitney. And even if she did have other clothes with her, there was never a chance for to change into them, since they went from the hospital straight to the airport.
Continuity mistake: On 3/17/06, Sam and Ivy had a conversation about Kay that was largely at odds with previous events and information from the show. In particular, they talk about how Kay pursued Miguel from a very early age. However, when the show began in 1999, Kay and Simone were in high school and their dialogue established in the very first episode that Kay had only very recently developed a romantic interest in Miguel. Furthermore, most of Harmony, including Sam and Miguel himself, didn't learn of Kay's interest until several years after that.
Continuity mistake: When Sheridan faked her own death in 2001 to escape from the drug cartel, she was buried alive. Timmy and Tabitha dug up the grave, and it was deep enough for Tabitha to stand in, upright, without her head reaching above the surface; it appeared to be the standard six feet deep. Then Julian had the grave filled in with cement after a token amount of dirt was shoveled in. But when the men broke apart the cement with their shovels, it was only about six inches thick. And when they finally dug through the cement and dirt, the coffin was also much closer to the surface than it had been before.
Continuity mistake: On 7/28/05 and 7/29/05, a few episodes after Harmony, which is in Maine, was hit by an earthquake, the two men at the Tsunami Warning Center say that a tsunami is heading directly towards Harmony. It had previously been said that the earthquake's epicenter had been just offshore of Harmony, so the statement makes sense. However, they then looked at a computer graphic that showed the tsunami originating from far out in the Atlantic and heading westwards towards the entire eastern seaboard, as if the quake had occurred in the central or eastern Atlantic instead of near New England.
Continuity mistake: On 7/6/05, Ivy mentions to Katherine that Rachel, Katherine's sister, had died before she, Ivy, married Julian. But since Ivy believes Alistair's story about Rachel dying in a boating accident, she should believe that Rachel died before Alistair married Katherine. And since Ivy is slightly younger than Julian, that means she thinks Rachel died before she was even born. Consequently, why would she cite Rachel's death in relation to an event in her life, rather than in terms of predating it altogether?
Continuity mistake: On 8/1/05, when the lamppost fell on T.C., you could see in the side view that T.C. was entirely in front of the lamppost from that perspective, so that they fell side by side, and T.C. landed perpendicular to the pole. Then, in the overhead shot immediately thereafter, T.C. was instead pinned by the street lamp, and it was lying mostly lengthwise across him.
Continuity mistake: On 1/29/04, Whitney tells Julian that she has been suspicious of him and Eve for weeks. But she only became suspicious after she saw them kissing, earlier that same day. Even though weeks had passed for the viewers, it was the same day for everyone in Harmony.
Continuity mistake: In July of 1999, in talking about Martin's disappearance, Pilar said that he left for work one morning, but never showed up there or at home ever again. However, flashbacks years later showed that Martin left Harmony with Katherine in the evening, after the Founder's Day dance that he attended with Pilar.
Continuity mistake: On 1/14/04, Sam tells TC that if someone had told him the previous month that Grace would be with David now, he wouldn't have believed it. But Grace chose David on 11/14/03, so it would already have been a fact during the entirety of the month in question.
Continuity mistake: On 6/23/05, Noah and Fancy kissed towards the end of the episode. Then they squabbled over who had followed whom to Harmony, both insisted that they were lifelong Harmony residents, and both accusatory asked each other, "Who are you?" before the police officer came up behind them and said, "That's what I'd like to know." Then, on 6/24/05, at the beginning of the episode, Noah and Fancy shared the same kiss, but then Fancy immediately and dreamily asked, "Who are you?" Then the police officer came up and delivered the same line as before.
Continuity mistake: On 11/22/05, Pilar and Martin learned that their daughter Paloma has been smuggling drugs. They are at the police station when Paloma admits this to them in the late evening. The next time we see them, on 11/25/05, it is morning of the next day, but her parents are only just recating to her statement as if no time had passed, instead of some twelve hours.
Continuity mistake: On 10/13/03, Gwen's memories come rushing back, of how Theresa contributed to her losing her baby. One of the memories is of seeing Ethan and Theresa making out on televesion. But she remembers it completely differently from how it really happened. When she was upset at what she saw on television while the doctors were there, what she was seeing was Julian and Rebecca denouncing Theresa's charitable contributions. When she saw the kiss, she was alone in her hospital room. In the flashback, the two scenes are merged.
Continuity mistake: On 3/4/05, Kay thinks about how Tabitha told her that "all Bennett women have powers." But it's not the Bennett women who have powers, but rather the Standish women. Kay happens to be both, because her father is Sam Bennett and her mother is Grace Bennett (nee Standish), but it's Grace's family that holds the powers, not Sam's. That's why Charity Standish and Grace's sister Faith had powers, as does Grace herself.