In episode 1.4 when Lucy and Ricky swap the cups (one contains sleeping powder Lucy thinks is poison) first Lucy's (containing the powder) is on the right and Ricky's is on the left. Lucy swaps them, so that they are now on the opposite sides. Then Ricky switches them back, meaning they are back to their original places. Then, Lucy sips the cup on the left (which was originally Ricky's cup and did not contain the powder). For the rest of the episode we are told that she drank the sleeping powder, but this would not be correct.
At one point Lucy runs the murder mystery she is reading under the faucet in the kitchen. As she is doing this, the book is shown to have photographs in it.
The dog trainer calls one of the dogs by its real name "Yorkie".
When Ricky and Lucy are dancing in the living room, the camera swings too far to the left, and the edge of the set wall and the adjoining bedroom set can be seen briefly.
Ricky has to hurry over to the desk to answer the phone. You can see the second camera in the shot when Ricky sits down at the desk.