During an unusual day at the hospital where a butterfly somehow gets into the lobby, Turk has left behind his Good Luck Charm bandanna, and Elliott promises a little girl that she will find her stuffed toy to get her through surgery. Turk and J.D. notice the butterfly lands on one of two people. This leads to two different timelines...
Timeline A: the butterfly lands on a hot girl's breast, and Carla mistakes Turk's Jaw Drop as him seeing another woman attractive after their engagement. Cue a Disaster Dominoes where Carla fails to find Turk's Good Luck Charm, the Janitor refuses to help Elliott, and J.D. and Dr. Cox have to diagnose a man with a rare condition. Dr. Kelso puts J.D. in charge of Dr. Cox, something that J.D. appreciates.
Timeline B: The butterfly lands on an old man's breast. Carla praises Turk for not looking at the hot girl, which leads to most people's days going well. The Janitor teams up with Elliott to find the stuffed dog, while J.D. arrives late to his rounds with Dr. Cox and finds a "Eureka!" Moment about their latest difficult case.
Tropes for this episode include:
- Actually Pretty Funny: Dr. Cox is amused by J.D.'s impression of him, complete with a girl's name and strict demeanor. He then gives back by pretending to have an Imagine Spot about candy bracelets. J.D. admits to himself that he would have one about those.
- Ambiguous Ending: The ending makes it unclear which of the timelines was the real one if it was the bad day that most people had or the good day that most people had. Both of the timelines end with J.D. pondering what if the butterfly had landed on another person.
- Bittersweet Ending: Timeline B ends this way, that everyone's problems are solved but the man with the aortic rupture dies anyway. Elliott gets the toy in time for the little girl's operation, Carla spends the night comforting Turk, who was doing the surgery with his lucky bandanna, and Dr. Cox reassures J.D. that they did their best. All you can do is hope for a better day.
- For Want Of A Nail: The butterfly's landing causes some differences:
- In timeline A, J.D.'s attempts to nope out of Carla and Turk's argument leads to him crashing into Laverne and making her drop all the smoothies she was carrying. He tries to apologize but she's rude to the Janitor, who can't help Elliott find the dog because of the sudden cleanup duty. In timeline B, J.D. barely dodges Laverne as he's listening to Carla praising Turk, and tries to poach a smoothie off her. The Janitor has time to help Elliott and dedicates the day to assist her.
- J.D. beats Dr. Cox to rounds in Timeline A, and Dr. Kelso jokingly puts J.D. in charge. To show that it won't bother him, Dr. Cox says that J.D. can lead the session; it leads to J.D. knocking himself out rather than getting into the elevator. Timeline B has the Janitor make J.D. late by excessively shaking his hand, and Dr. Kelso chides J.D.. The Imagine Spot changes from J.D. playing banjo to Dr. Cox playing banjo and Dr. Kelso playing a washboard.
- In Spite of a Nail: There are some similarities in both timelines:
- Laverne brings smoothies, though apparently, they are for the nursing staff. She keeps J.D. from grabbing one in the good timeline.
- Carla goes back to the apartment to try and look for the bandanna.
- The man with the aortic dissection still dies. As Dr. Cox tells J.D., the surgery has a rare chance of success even if you catch it ahead of time.
- Pet the Dog:
- The Janitor helps Elliott find the stuffed dog in time for the little girl's surgery.
- In both timelines at the end of the day, Dr. Cox tells J.D. that it was a rare chance that they could have actually saved the guy. An aortic rupture is very difficult to diagnose, let alone operate on; what's important is that they did their best with what they had.
- Wham Shot: The flatline happens at the end of the good timeline, meaning that the guy with the aortic disruption still died.
