Revealing mistake: On 10/13/03, Ivy and David are discussing their plans in normal speaking voices while the unsuspecting Grace and John stand within arm's reach. They are well within earshot, yet the audience is expected to believe that Grace and John can't hear them.
Revealing mistake: On 3/3/04, Rebecca had a flier for the benefit concert at the Blue Note. Above a picture of Whitney, it boldly advertises a "Benifit." Notice the misspelling.
Revealing mistake: On 12/24/03 and 12/25/03, Sheridan is supposed to be breastfeeding baby Martin. But Sheridan's shirt is barely unbuttoned, and pulled aside only marginally (and mostly from the opposite side of where the baby is). For his part, the baby is not even turned towards Sheridan's body. So, the way the scenes are shot, there's no way he could be nursing.
Revealing mistake: On 9/23/03, Theresa was in the closet talking to herself about Gwen and her baby. She very obviously flubs the word "because," pronouncing it more like "bikyiz."
Revealing mistake: On 12/26/03, Ethan tells Woody that he doesn't want people to know that they're there together. But throughout their conversation, Ethan constantly turns directly towards Woody and speaks with him quite loudly. Woody is practically hanging out of his seat as he leans towards Ethan. Every couple of scenes, Ethan reiterates the need for discretion, but neither of them does anything about it. It's really not that hard to talk out the side of your mouth while sitting back to back.
Revealing mistake: On 11/5/03, Luis is begging the divers to continue searching for Charlie and the baby he believes to be trapped with her in the submerged car. Beth and Mrs. Wallace are watching these events on a news broadcast that includes changing camera angles and dramatic closeups. It looks completely unlike a real news report.
Revealing mistake: On 2/20/07, when Simone first approached Rae's dead body in the casket, the rise and fall of Rae's chest and stomach, due to the actress' breathing, was quite visible.
Revealing mistake: On 10/27/03, Tabitha was visited by the ghost of Timmy. When he approached little Endora, it was apparent from the back of his head that it wasn't Josh Ryan Evans. This was obvious even without the knowledge that the young actor died more than a year earlier.
Revealing mistake: On 1/11/07, Fancy turned off the light in her bedroom after Luis left to talk to Sam. Right after she did that, the offstage set lighting could be seen to become brighter so the scene would still be lit.
Revealing mistake: On 9/6/05, Fancy told Alistair that she wanted to go to Paris, but he forbade it. She then complained that she gets bored staying in one place to long, to which he responded, "Then you're gonna have to teach yourself to amuse yourself. You gotta learn things to be alone." After that, his eyes glazed over slightly before he looked off to the side and moved his lips wordlessly for several seconds and then continued with his dialogue. The actor must have completely dropped a line, because this quotation made no contextual or semantic sense.
Revealing mistake: During the 6/28/04 episode, Theresa falls off a cliff. As she falls, the cliff indents and moves, making it obvious that the "cliff" is just some sort of brown burlap material covering the set.
Revealing mistake: Season 1, Episode 3, 7/7/99. Just before Theresa bumps the ladder that causes the paint to spill onto Ethan, a camera shot shows the pan, and it's plainly obvious that it's water.
Answer: I don't know about good not wanting them to be together, but I know the evil side doesn't want them together because once they sleep together, then Charity's powers will multiply, and she will be a driving force against the evil darkside.