The Murder of Sherlock Holmes - S1-E1
Continuity mistake: During the scene at the train station, Jessica's nephew introduces to her Kitt Donovan from the publishing company. Just as he says "in public relations", a man pops in the foreground - it is an extra that walks out of the rail car. In the reverse shot that follows, the same extra is only then coming out of the train. (00:09:35)
The Murder of Sherlock Holmes - S1-E1
Continuity mistake: Episode 1-0, "The Murder of Sherlock Holmes"; Mr. Giles opens the door of the antechamber of his office, finally putting an end to Jessica's long wait. Grady right away at the first click of the lock takes his hands off his pockets and tidies up his sleeves. But in the next shot when Grady actually enters and talks to the secretary, Grady is still with his hands on his pockets repeating the gesture. (00:10:10)
The Murder of Sherlock Holmes - S1-E1
Continuity mistake: When Jessica's publisher at the beginning of the party holds her hand and kisses it, he is holding her hand in different ways in the separate shots. (00:18:20)
The Murder of Sherlock Holmes - S1-E1
Continuity mistake: Mr. Giles holds the telephone as he interrogates the private eye, who answers in a rather defiant way to the threat of "the local constable" getting involved. So Giles puts the receiver down, but notice that in the first shot he is passing it from the right to the left hand. In the close-up it is the right hand to hang up, though. (00:23:15)
The Murder of Sherlock Holmes - S1-E1
Revealing mistake: In part 2 of the episode, when Jessica is mugged, Angela Lansbury is replaced with a younger and thinner stunt double twice: when she runs away and when she protects herself against the wall.
Deadly Lady - S1-E2
Revealing mistake: When Howard Duff's two daughters enter the police station to identify his body, the cop pulls back the blanket. Howard's eyelids are moving even though he is supposed to be dead.
Visible crew/equipment: Jessica is at the crime scene with the detective and walks from the back of the set to the cemetery. The moving shadow of the camera is cast on a rocky wall. (00:17:33)
Visible crew/equipment: When Jessica is on her horse at the barn, there's a crew member lying on the floor, watching out for Angela Lansbury.
Revealing mistake: After Denton falls off his horse, Jessica arrives and jumps off hers. Her stand-in is a much younger and thinner woman who looks nothing like Angela Lansbury.
Continuity mistake: When Jessica (a stunt double) rides her bicycle at the start, her red scarf is tied around her waist. A shot later, when the real Jessica is shown, the scarf hangs around her neck.
Visible crew/equipment: When Jessica gets trapped in the car, lighting equipment is reflected on the window.
Death Takes a Curtain Call - S1-E9
Revealing mistake: When the cops arrive at supper time at Jessica's door, the background is a blatant painted backdrop. (00:31:45)
Death Takes a Curtain Call - S1-E9
Continuity mistake: The way the sheriff hands over the phone to Major Anatole Karzofman differs between the first and second shot, with the handset turning 180ยบ.
Death Takes a Curtain Call - S1-E9
Continuity mistake: When Jessica questions Eddington, he has his glasses on. An instant shot later, they're on his hand.
Death Takes a Curtain Call - S1-E9
Continuity mistake: When Jessica and the Russians escape in the Rolls Royce, the back projection is not continuous between shots. On the right side window, the place swaps between a modern city and a park. On the left window, the same people walking around are played several times.
Death Takes a Curtain Call - S1-E9
Visible crew/equipment: When Jessica and the Russians exit the theatre, the whole filming crew and cameras are reflected on the car's fender.
Continuity mistake: After Kellijian aims to choke his wife, they kiss. Right afterwards, the position of her left arm on his body is not continuous between shots.
Revealing mistake: When Cagliostro is stabbed, there's a protruding rectangular pad under his shirt where the knife is stuck.
Revealing mistake: When Jessica rides on the motorcycle, one can see it's a much younger and thinner stunt double who doesn't resemble Angela Lansbury.
Continuity mistake: When Jessica talks to Lt. Bergkamp, she takes her left hand to her ear to improve her hearing, but from the opposite shot, her hand is lowered.
Chosen answer: This is the very reason my brother and I used to jokingly call the show, "Murder, She Caused." It's amazing she was ever on anyone's guest list for a party, given the likelihood someone would end up deceased. As to your question, most of the time, Jessica Fletcher would have had an air-tight alibi, as she was in a room full of people, or her whereabouts were accounted for when a murder occurred elsewhere. It also seems to me that there were episodes where she, purely with respect to opportunity, could have been a suspect. I believe she even acknowledged that as a logical possibility from time to time, even though she knew, of course, she was not the killer. However, the investigation would obviously rule out the possibility of her involvement, eventually.
Michael Albert