Plot hole: On 10/6/03, Sami tries to listen at the door when Marlena meets with Kate in the latter's office at Basic Black. She says to herself that she wants to find out Kate's secret. But Sami already knows that Kate was once a prostitute. Sami used evidence of Kate's past to blackmail Kate and Victor; Kate's son Austin found out, and that was one of the reasons why he left Sami at the altar. Even though Sami can't know for sure that this is the same secret that is now in question, she is acting as if she knows nothing incriminating about Kate.
Plot hole: On 12/08/03, Belle and Shawn talk on the phone, and Belle briefly mentions something about how much she's enjoying Paris. But Belle was sent to Milan to keep her safe from the killer, and Jan also said that she had seen Belle while she was in Milan herself. Nobody ever said anything about her going to Paris.
Continuity mistake: On Thursday, 10/13/05, Belle saw Shawn and Mimi together on the roof. At the end of the episode, she was climbing down the ladder when her foot slipped and she appeared to fall. Belle was not seen on 10/14/05, and then at the beginning of the episode on 10/17/05, they showed a completely different scene where Belle was climbing down the ladder and her foot almost slipped from a rung, but she didn't loose her footing nearly as much as she had the first time these events were shown.
Factual error: On 9/19/05, Kate mentioned something to Billie about Billie being Lucas' "only sister." But Lucas has three sisters: Billie, Jennifer, and Cassie. All three are actually his half-sisters. Even if Kate wouldn't think of Jennifer, she would certainly remember her own daughter Cassie.
Plot hole: Around 3/14/05, the Jennifer impostor told Jack that it was too late at night to get Abigail from Chelsea's house where she was staying. Jack agreed that it was very late at night, and they also talked about how late it was when the impostor told Jack that the ISA wanted to debrief him right away. Then, later that same night, it was Alice's anniversary party, which wouldn't make sense if it had already been late at night to begin with.
Plot hole: Belle, Philip, and especially Mimi have been concerned about paying the rent on the loft over the course of their living there in various combinations in 2003-2004. However, when Brady first moved in there in 2002, it was stated that his and Belle's father, John Black, owned the loft. So nobody should have to pay rent on it at all.
Factual error: When Abe is shot, Bo, John, and even the paramedics need some training in their CPR. First off, Bo and John do 3 chest compressions and 1 breath (or 2 I can't remember) when it's supposed to be 15 compressions and 2 breaths. Then, when the paramedics take over, they aren't even doing the chest compressions the right way. They compress with their fingers rather than their palms and they look like they're compressing in Abe's ribs rather than up by his breastbone. I know it's TV and that they can't give real compressions, but they could at least make it look like they know what they're doing and do CPR the right way.
Continuity mistake: On 1/6/05, one of the police officers said that the paint on Bo's SUV matched the residue on the curb. However, Zack was hit just after he stepped out from between two parked cars. Therefore, there would have been no residue on the curb at the accident site.
Continuity mistake: Victor and Doug were both murdered on the night of Valentine's Day, which on the show lasted until the 3/11/04 episode. The next day started on 3/12/04, and turned out to be St. Patrick's Day when we saw Rex and Philip enjoying green beer at the Cheatin's Heart. We know that it was supposed to be the very next day, because characters talked about the murders that happened "last night." But the two holidays, shown here on sequential days, actually fall on February 14 and March 17, respectively.
Continuity mistake: When "John Black" was proven to be Roman Brady, DNA tests were used to prove he was really Roman with plastic surgery. Years later, after the real Roman Brady returned and John Black was once again John to prove who was Belle's father, all it took was a simple blood test; but years earlier, they had the same blood type.
Plot hole: On 4/16/04 and 4/19/04, John told Marlena that he had an idea that could prove Marlena's innocence, but could also potentially be fatal. Then, on 4/20/04, John acted surprised and upset when he learned that Father Jansen's possession test could have killed Marlena. But John was previously a priest - he even exorcised Marlena when she was possessed in 1995 - and definitely seemed to know that the procedure could be deadly, so his shocked disposition makes no sense.
Continuity mistake: On 2/8/06, Abe Carver said that "two years ago," the recently deceased Zack had given him "the gift of being a father." But Zack, who was originally the Carvers' adopted son, was born in 2000, over five years previously. Perhaps Abe was thinking of his second son, Theo, who was born in 2003.
Continuity mistake: Ever since Bo and Billie learned that their supposedly stillborn daughter Georgia might be alive, they've repeatedly talked about how she would be sixteen years old now. When they received a package that supposedly contained Georgia's hair, it was labeled with a birth date of 5/22/9-, with the last digit hidden by Bo's thumb. But if Georgia was born in 1990 or later, she wouldn't even be fifteen yet.
Continuity mistake: In December of 2004, Bo and Billie flew to Europe at night to look for their daughter Georgia. On 12/3/04, it was shown to be daytime at the castle where Roman and Marlena were being held. Then, on 12/13/04, Bo and Billie arrived at the castle but it was dark outside. On 12/15/04, they were inside the castle and it was again full daylight outside. The whole time, it just got later and later on the same night in Salem.
Continuity mistake: At the end of the episode on 4/10/06, Billie realized that the trapped girl's cell phone was Chelsea's, and at the same time Bo went into the sewer and discovered that the girl was Chelsea. At the start of the episode on 4/11/06, Billie yelled down to Bo that the girl was Chelsea as soon as she realizes it, and Bo then continues into the sewer, already knowing that the girl is Chelsea before he reaches her.
Plot hole: On 10/8/04, Hope drew a comparison between the current situation and the movie "A Shark's Tale", saying Zach wanted to go as the shark that didn't eat people. But Hope had been trapped on an isolated island for weeks, since well before that movie came out, so how could she know anything about it?
Other mistake: On the end of the 3/15 show, Jack is outside searching for Jen and then the fake Jen comes out of the house and tosses her hair to prove that she is the real Jen. However, Jack saw the real Jen before and she was wearing a black outfit, while fake Jen is in purple. He should have known that the Jen that comes out isn't the real Jen.