As anyone who's ever worked on a film - or indeed literally ANY creative endeavour - will already be aware, visions change all the time. By the time a film-maker emerged from the editing booth, the film they're working on can be completely unrecognisable from what it was initially intended to be. Sometimes that's because scenes conceived on paper just don't work as well on film, sometimes it's just different preferences... Sometimes studios intervene.
The strangest - and both most chaotic and probably most brave - changes are those that come right at the end of things. When sweeping transformations happen on the fly and scenes that were marked up as the supposedly final version end up being changed fundamentally. That's not always for the better, obviously, but it's quite shocking to see how many important movie scenes were pretty much bolted on at the last minute.
Bruce's Phone Number - Bruce Almighty
This wasn't so much a creative change last minute as one made necessary by someone not diligently checking up on a small detail in a movie that could quite easily have ruined a normal person's life.
In Bruce Almighty, God contacts Bruce using a real phone number - 776-2323 - rather than the fictional 555 numbers films generally use, which inevitably led to people genuinely ringing the same number wanting to talk to God. Because, of course, Bruce Almighty was famously a documentary. Incredibly, of the three people with the real number, one was a man who worked in a North Carolina church who was called Bruce.
The issue meant that Universal had to retrospectively change the number digitally to a 555 number for the home release.