Yes, We Have No Havanas - S4-E1
Continuity mistake: At Fidel's funeral, Sophia talks about him awakening feelings that she had not felt in 35 years. But earlier in the episode, Dorothy said that her father/Sophia's husband has been dead for 27 years. Also earlier, Sophia claimed to have showered with a man 22 years ago.
Continuity mistake: Blanche's attitude towards birthday parties changes throughout the show. Originally, she disliked them, but Rose changed her mind when she invited several men Blanche desired, as is seen in a flashback. In the same episode, the Golden Girls threw a surprise party for her which she was happy about. In a later episode, she hates birthday parties again (with Rose being baffled she doesn't like them), but is happy again at the end of the episode when Rose invites men to her party.