Episode #17, "Lucy Write a Play", a few minutes after Lucy finishes the last page, Ethel walks in and there are two scripts, one for Lucy and one for Ethel.
Episode #33 "Lucy's Schedule", Phoebe Littlefield makes a mistake when she says "if my Alvin sees what he likes here tonight..." instead of "if my Alvin likes what he sees here tonight..."
Episode #9, "Drafted", Lucy believes she hears Little Ricky crying, but Ethel explains that it's just Mrs. Trumbell's cat. (Hmmm... what ever happened to no pets allowed?) Also, Lucy boo booed. Little Ricky was not born yet in the first season. (thanks to [email protected])
Episode #80 "Ricky Minds the Baby", after Ricky tells the story he later says to Lucy that he never heard "A mice giggle so loud". But she never really made any noise when she laughed, all she did was smile.
Episode #98 "Lucy Cries Wolf", a neighbor calls and tells Ricky that Lucy is out on the window ledge, Ricky tells Fred and Ethel that she's out there by writing something on a piece of paper, he didn't write enough to tell who told him that Lucy was out there, so only he knew who called. Later when he closes the window and Lucy comes in, they say that they knew she was out there and Ethel says who called and told them, but Ricky was the only one who knew who called.
This is a blooper for every Connecticut episode. As all Lucy fans know, in the Ricardo's kitchen, there is a stairwell leading upstairs, but where does it go? If you look up the stairs out in the front of the house, you can see that it doesn't go over far enough to reach the kitchen.
Episode #108 "Getting Ready," Fred drives off to the right in the Cadillac, and the camera follows him. You can see far down the street and part of the audience!
Episode #128 "Lucy Visits Graumans", at one point after she gets her foot stuck in the cement, she pretends to be sleeping in Fred and Ethel's hotel room, but get a good look at the room. It is seen in a later California episode ("The Great Train Robbery" #132) and it is completely different!
Episode #168 "Lucy Hates to Leave" The scene opens with the clock on the wall showing 2:00 a.m. Ricky is pacing the floor, worried about their big investment, all the while smoking a cigarette. Lucy gets up and while consoling him, he puts the smoldering cigarette in an ashtray. After reassuring him, Lucy and Ricky get back in bed and Ricky, feeling better, goes to sleep. The next scene opens with the clock on the wall indicating 3:00a.m.,an hour later. Now it's Lucy who can't sleep. They both get up to talk again and you can see the cigarette in the ashtray is still smoldering! I don't know what you might think, but to me, a cigarette cannot smolder as much as that one did for an hour.
In the movie "The Long, Long Trailer" there is a scene near the end of the film where Nicki told Tacy to throw out all the rocks and other things she had collected, because they were going to climb to 8,000 feet the following day and couldn't afford the extra weight. They started up the mountain, made a curve, and drive past the camera. In the reflection on the side of the trailer there are figures of at least three people. One behind the camera, one with a light reflector, and another standing to their left (apparently the director). Unless one looks closely they are not noticed.