Reddit reviews The Pentagon Wars: Reformers Challenge the Old Guard

Always the best example. That thing has been around since the 30's and is still used on a lot of military vehicles.

A runner up is the B52, which has been around since the early 50's and is expected to continue until 2040. On that note, it seems like there's a possibility that the A10 will end up like that as well, because even though there's always talk about it getting canceled (even Rumsfeld talked about ending it IIRC) it keeps getting sent into combat. Side note: while the book The Pentagon Wars is predominantly about the Bradley IFV, it does have some great bits early on about the development of the A10.

Other have mentioned basic rifles, and yeah, that's a good one too - we've been improving the M16 since Vietnam, with the M4 being the current incremental evolution, though it's interesting to see the technology you can put on the rifle (targeting lasers, optics, etc).

There's a ton more (U2, C130, etc), so the last one I'll mention here is the SINCGARS radio, which has been around since the 80's and has evolved over time. There were attempts to develop new radios, but they didn't work out.

The movie is a comedic retelling, but the facts are legit. Burton - the author of the book the movie's based on - was a bird colonel who spent over a decade in the procurement machine. And the Bradley was eventually beaten into a functional and very feature capable IFV, so in the end, it was worth it.

The tracked transport carrier you're thinking of is most likely the M2 Bradely Infantry Fighting Vehicle, which was put in to service back in 1981. That would make the movie The Pentagon Wars (1998), based on the book by retired Air Force Colonel James G. Burton. The Burton in the movie was portrayed by Cary Elwes (sporting a passable American accent), with Viola Davis, Kelsey Grammer and Richard Schiff as supporting cast. The whole movie is up on YouTube here, though one of the best parts about how the Bradley "evolved" can be seen here.

I think there are more common criticisms of the military industrial complex than "they make things used in war". The OP might be thinking more about the history of corruption and the undue influence of the military industrial complex on American politics (at the confluence of money and war). For instance, as detailed in The Pentagon Wars, such as the scandal involving the construction of Bradley tanks, which were more or less deathtraps (fun version). Of course there are people who object to American imperialism more broadly (quite correctly) but they tend to use broader language than "the military industrial complex" which is a more... non-partisan problem.

Plenty of militaries around the world allow criticism of the inner workings of their procurement strategy. Case in point, the US Army has not been destroyed by the fact that their officers are allowed to write books.

Anyone interested in the waste and nepotism mentioned above should see the movie The Pentagon Wars, or read the book of the same name by retired USAF Colonel James G. Burton.

It's Burton's story of his 14 years stationed at the Pentagon, centred around the development of the Bradley fighting vehicle, whose development required 17 years and $14 billion, not including the purchase of the actual production vehicles.

Burton characterizes the Pentagon's spending of the public's money as a dirty business, one that too often has nothing to do with national defense, one in which secrecy and deception are valuable currencies. "Sadly, I have seen program managers lie to high-level review boards, generals lie to civilians, civilians lie to generals, and both lie to Congress and the American public. Seldom is anyone held accountable. On the contrary, many are rewarded for their behaviour."

You do realize it's based on a factually-accurate book, which it follows closely, right?

https://www.amazon.com/Pentagon-Wars-Reformers-Challenge-Guard/dp/1612516009

Obviously actors are going to play up the comedic effect, but the main plot is pretty accurate.