There is basically an unlimited amount of interesting information about the franchise and so much is hidden in dark corners,
Below are a few highlights from my research, the full 39 page document is here:
https://docs.google.com/document/d/e/2PACX-1vSQoNxFJXAI7uroubKC-BCKp0JbaHzOhU_xvAjuPdu72GO0hGxel553bbZGRklYIUk9KLoiw2JCAvr2/pub
Or you could just watch the explanation in video form:
https://youtu.be/0ahJklOPbn8
From Layer 2 - George Lucas
Brian De Palma said he was very disappointed with the work of writer Robert Towne's work because he believed the script needed character flesh-out and clever scenes, while Towne rewrote the entire piece. Towne kept pushing a Notorious-style romantic espionage triangle. This lead to George Lucas chiming in to criticize this as unfitting for the film. Lucas feedback led to a completely new scene, he suggested a 'spaghetti scene,' a table scene where the team sits around and explains what is going on. That became the reshot safehouse scene near the beginning. Actress Kristin Scott Thomas was not cleanly available for the reshoot, which is why Sarah appears oddly separated from the rest of the group in the scene.
From Layer 4 - Julia Baby
Julia and her new husband Erik originally had a baby in the climax of Fallout, but the baby character was cut from the project just days before shooting
From Layer 7 - SUV Yank
For the shot of Ethan being yanked into the SUV on the bridge scene in MI3, Cruise eventually told the crew not to warn him when the ratchet would fire. The take used in the film captures his genuine surprise as he is pulled sideways into the vehicle. VFX Supervisor Todd Vaziri says he preserved Cruise's physical performance in the bridge blast shot: he did not alter a single pixel of Cruise's body, did not remove frames, and did not warp or speed-ramp Cruise to make the stunt look better.
From Layer 8 - Nobody cares about Walker
Fallout contains a running gag where Walker tries to tell people his name and nobody cares. For example he introduces himself to Ilsa at the end of the bathroom scene and Ilsa, not even looking at him, answers "Yeah? You're welcome" McQuarrie says it became a thing that people do not care who Walker is and nobody cares.
From Layer 9 - Joe Biden
Then US President Joe Biden and Deputy White House Chief of Staff Bruce Reed reportedly watched Dead Reckoning Part One at Camp David, and Reed later said the movie gave Biden even more to worry about regarding AI before the executive order on AI safety.
All sources are cited in the document and the video
