In syndication re-runs, The Simpsons normal opening sequence is used instead of the one where Homer trys to vote for Barack Obama or Mitt Romney and winds up working in a china factory.
The underground water cavern looks like (and drains like) a human bladder.
The credits were done in cursive writing, the same writing style Lisa learned to write in this episode.
Marge's new car's plate number is PABF18, which is the production code of this episode.
This is the second episode where a sinkhole has caused part of Springfield to collapse, and the third time in the series. The first being "Who Shot Mr. Burns? (Part One)", and the second being "The Movie".
Marge is driving her red car again in later episodes. Meaning, it must have somewhere been recovered or Marge got a car similar to the old one.
In this episode, Marge is shocked to find that Homer has a low sperm count, but in "Eight Misbehavin'," Marge already knows that Homer is sterile from working at the nuclear plant for years (which was also mentioned on season three's "Brother, Can You Spare Two Dimes?")
A line of Kent Brockman's nose is missing when he is interviewing Moe. The line reappears when Barney wakes up.
The time the drop of water falls is exactly 20 seconds. Marge, Lisa and Bart could not get ready to school in that time.
In the first scene of Marge driving to school, Lisa and Bart are far apart. But in the next shot, they are close together.
When Marge walks out of the house to complain about the leaky faucet the second time, she's wearing boots. However, after the shot switches to Homer and back to her, she's wearing her regular shoes.
For some reason, neither Homer nor Marge ever considered adoption.