Continuity mistake: In this episode, Larry is a really poor sounding singer, but in the episode "Strangers in the Night (6-12) " in the previous season, Larry sang perfectly without any problems.
Continuity mistake: After Furley tells Jack about picking up the pot, he says, "Of course, it'll cost you." Later, when the cop listens to the recording of the conversation, the tape has Furley saying, "Of course, it's gonna cost you."
Jack Goes the Distance - S7-E16
Continuity mistake: In many earlier episodes, Jack always mentions he was a boxing champion in the navy. But in this episode, Jack admits he lost every fight in the navy.
Answer: I believe you are referring to the artwork of Alphonse Mucha. On the wall next to the front door was "Feather" (which is one half of "Primrose and Feather"). Above the telephone in early episodes was "Zodiac". Also seen through The Apartment was "Spring" and "Autumn".