While You Were Sleeping - S1-E2
Other mistake: When Sherlock was slapped, he later says he was surprised because the girl who slapped him was a "lefty." Then he rubs his right cheek and says it's leathery from all the slaps he's gotten, while the left is soft. This is backwards - anyone hitting him with their right hand would hit his left cheek.
Character mistake: They are in the interrogation room questioning the fiancé of the scientist Natasha when the captain says, "the blood we found at the scene of your fiance's murder, it didn't belong to Bobby Cordero." The characters name was Benny Cordero, which the captain says correctly a few lines later. (00:33:25)
Continuity mistake: Sherlock and Watson are riding in a limousine. They are seated on the back-facing seats of the limo. Thee are 2 passengers seating on the back seats. The street background visible through the back and side windows shows traffic and the limo moving forward. Some shots of Sherlock show the background traffic moving in the right direction (backwards) and one shot shows traffic moving in the opposite direction, as if Sherlock was seating on the back seat or the limo was moving In reverse.
Character mistake: When looking at the car near the start, Sherlock says he can tell by the pattern of the bullet holes that the gun was fired in 3 round bursts. But when we saw the attack earlier, the gun fired in bursts of different lengths.
Continuity mistake: While playing the piano in Justin Guthrie's apartment, he is bare handed. In the next scene when he gets up to point at the blood, he is wearing gloves. (00:24:12 - 00:24:42)
Character mistake: Sherlock states that Sean Figueroa has "such blue eyes" even though he has brown eyes. (00:39:05)
Continuity mistake: The brownstone has two front doors, an outer door and an inner door. In scenes before this one and after this one, the outer door is made of wood and the inner door has a large glass panel, at the top, but in this episode the outer door has a large glass panel, at the top, so they can see who it is before opening the door.
Continuity mistake: At the beginning, the way Holmes holds the photo is different in consecutive shots. (00:01:00)
Visible crew/equipment: The set light is reflected on Joan's car as she returns to it after talking to the victim who survived. (00:21:35)
Continuity mistake: Early in the show, when Sherlock is making eggs, he adds milk and sets the jug down. The camera shifts to Watson and back to Holmes, which shows the jug missing. Watson then walks around Holmes and sets the jug down in the spot it was in previously.
Other mistake: When Sherlock and Watson look at the coffee order from the trial it has the names of the 4 jury members who robbed the vault. Not the original men that did the robbery.
Factual error: The number plate on the black cab is GW22 ARY. This won't happen until the year 2022. (00:28:20)
Continuity mistake: Just before Sherlock and Detective Bell enter the dead professor's office, both are putting on gloves. Sherlock puts on the left first and has partially put on the right. As they enter the office, Sherlock still hasn't put the right glove on at all - he's just starting to do so. (00:05:30)
Continuity mistake: When Sherlock first accuses Irene of working for Moriarty, he pins her to a bookcase. When she shoves him away and breaks free, her hair ends up arranged with some strands in front of her. During the following minute, those strands repeatedly switch back and forth from behind her shoulders to in front of them. (00:38:25)
Continuity mistake: While Joan and Sherlock are chatting, Joan is trying to make peanut butter and jelly sandwiches, but the shots alternate between the two and Joan repeats her movements, wipes the peanut butter over and over on the bread, and changes her mind with the jelly bread.
Continuity mistake: In the beginning, Joan and Sherlock are chatting in the living room. Joan has her hands in her lap, then she is resting her right arm on the arm of the chair.
The Rat Race - S1-E4
Continuity mistake: In the final scene Watson finishes tying her shoelaces. Next shot she is still tying them. (00:41:40)
The Rat Race - S1-E4
Continuity mistake: Watson has just been ambushed with a date by her friend at the very beginning. She is reaching for her coffee cup. In the immediate next shot, her hand is down by her side. (00:03:15)
Other mistake: Near the end of the episode Dr. Watson states, "Look at the time, happy 'real' anniversary." - referring to Sherlock's one year anniversary of sobriety. The scene then cuts to a flip clock. However, the clock is set to 12:07 PM - not AM as it would be if a new day had begun. (00:41:20)
Answer: I'm the same person who asked this question. I discovered it was Molly Price whom I recognized from Third Watch.
It should be noted Donna was Jim Fowkes‘ secretary. Donna killed Peter.