Homer skips a date with Marge so he can buy a lottery ticket; when he wins a million dollars, he fears Marge's reaction to having blown off the date for a chance at fortune and he keeps his winnings a secret while showering the family with anonymous gifts. Meanwhile, Lisa helps to keep the senior citizens at the Springfield Retirement Castle stimulated with some video games.
Homer and Marge are scheduled to do a singing toast at Homer's cousin Valerie's wedding, causing Marge to become nervous, due to her fear of embarrassment. However, Homer tells her not to worry, saying that he will make sure they do not mess up. Homer gets a fortune cookie stating that today will be his lucky day, but he does not believe so. However, he starts to believe it is when he crashes into a vending machine causing all of the snacks to fall out on him, and finding his favorite CD. He then goes to the Kwik-E-Mart for a lottery ticket, even though he has to go to the wedding and sing Potato, Potato with Marge. After a long time of waiting, Homer gets his lottery ticket, but the wedding has ended, with a terribly embarrassed Marge. When he takes his eyes off the road for a second, he crashes off the ramp, narrowly missing Ricardo Bomba, who is driving on the road. However, when Bomba is looking away, he crashes into the cliff, presumably killed. Homer wakes up in the hospital after the crash, and realizes he won the million dollar lottery. Homer does not want Marge to know he missed the wedding to get a lottery ticket, he has Barney pose as the winner, giving Homer the money. Not wanting Marge to know he won the money, he drops things his family wants in different places. However, when Homer tries to get money out of the tree he hid it in, Bart discovers that he won the lottery, and tells Homer that if he does not do what he asks, he will tell Marge that he went to the Kwik-E-Mart instead of the wedding. Tired of being Bart's slave, Homer decides to tell Marge himself and get it over with. Taking Marge on a hot-air balloon, he reveals he won the lottery, causing Marge to become very glad, until he tells her he spent it all, leaving them poor as usual. However, Marge does not care, saying they have each other. They then sing the song they were supposed to sing at the wedding together, off in the sunset.
Meanwhile, Lisa discovers that the senior citizens at Grampa's nursing home do not have any entertainment, she decides to buy them a digital TV converter. However, while at the store to buy it, she discovers Mr. Burns feeling very happy playing Funtendo Zii Sports, she decides to buy this for the senior citizens, hoping they will feel younger and happier. When playing the Zii, the senior citizens feel very happy and feel younger. But however, the nurses at the home have to work extra hard after their work-out, prompting them to wash the Zii in the dishwasher, causing it to break, and the senior citizens turn back into their boring selves.
Singer Chris Martin of the band Coldplay guest starred as himself in the episode. Coldplay drummer Will Champion commented on the appearance: "We actually went to a read-through for an episode about seven years ago. We were staying in Los Angeles and our friend—our manager—I think knows someone to do with the whole program. So we just went down and had a listen, while all the actors were reading their lines and we were just blown away that we were even there. From then, we just thought it would be amazing to make it on an episode. It's definitely one of those moments where you have to pinch yourself. It's been around for so long."
The episode featured a new character created by the winner of the "Best. Character. Ever." contest, in which fans could submit their own ideas for a new, and possibly recurring, Simpsons character. Over 25,000 entries were sent in. The winner of the contest was Peggy Black from Orange, Connecticut, who created the character Ricardo Bomba. She described Ricardo as "someone that all the women love and all the men want to be." Black's inspiration for the character came from the fact that there were no characters like him on The Simpsons, and she thought Springfield needed "something like a Casanova." As part of the winning prize, Black was sent to work with the show's producers in Los Angeles. She worked with the animators to bring the character to life; "I described the character and they drew him so I could see if that was my vision of him. It's amazing to see how they captured what I imagined. He's over the top." Executive producer Al Jean was one of the judges of the contest, which he described as "a thank you to loyal fans." Jean also noted that there is a possibility the Ricardo character might appear on the show again. The original plot was that Homer won the million dollar lottery and spends the money for Coldplay to perform for him and Bart, but Bart keeps on going to the bathroom so Homer and Coldplay decide to find out why Bart suddenly has to go to the bathroom.
In its original American broadcast, "Million Dollar Maybe" was viewed by 5.11 million viewers and got a 18-49 Nielsen Rating of 2.4/6 becoming the least viewed episode of the season and series mostly because it aired against the Grammy Awards and Pro Bowl and was well below the seasonal average of 4.3, but still was the second most viewed show on FOX that night after Family Guy. The episode ranked 23rd in the weekly 18-49 ratings ranking 10th on FOX.