These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Harsher in Hindsight: Several of the A's Beane was praised for signing in the book were later implicated in the Mitchell Report. Most notably, Jason Giambi.
Hilarious in Hindsight: Some baseball fans snarked about the movie's timeliness considering the A's had recently fallen into a string of mediocrity note including the 2011 season which the film was released, the A's had gone five years without a winning record and Billy Beane's roster strategy being called into question. After the film's release, the A's revived their Moneyball success by winning their division the next two seasons (2012-13), a division that features two rival teams who were among the six highest payrolls in baseball.
The only negative review of the film among Rotten Tomatoes' Top Critics came from the San Francisco Chronicle; the San Francisco Giants are of course the interleague Bay Area rivals of the A's.
Beane pumps up rookie Carlos Pena as a future All-Star to Tigers GM Dave Dombrowski in order to get his deal done. Pena actually would go on to be a future All-Star, although it would be after he flamed out in Detroit and had a Career Resurrection in Tampa Bay.
Billy's line about the A's—"There are rich teams, and there are poor teams...then there's fifty feet of crap...and then there's us"—became disturbingly literal in 2013 when a stadium plumbing backup filled the Oakland locker rooms with raw sewage.
Tearjerker: It's very hard not to get misty-eyed while listening to Beane's daughter sing for him, especially if you're a father.
The scene where Beane's got to tell Magnante that he's being sent to the minors. Even worse when you see the associated deleted scene where Beane mentions that Mags is playing scared - constantly worrying that his next pitch will be his last in the Majors.
The Woobie: Beane trying so hard to put together to win the World Series with so little money and he still hasn't yet.