Cliché Storm: The film series quite deliberately uses every single trope common in the kind of hyper-violent '80s action films where Stallone made his career.
In 2009, a year before the film's release, Mickie Rourke had an appearance in WWE thanks to his success with The Wrestler in order to work a storyline with Chris Jericho. As at first Rourke didn't trust the company, he brought with him an entourage of tough guys, including MMA fighter Frank Shamrock, boxer Clint Coronel and an Israeli bounty hunter, just in case he got double crossed or something. Naturally, after the film came out and this was made public, a fan in this page was quick to point out that Rourke had assembled his own real team of Expendables.
Talking about WWE, it has adopted Diamond Eyes as one of their themes. From a film that featured a classically trained wrestler (who also trained professional wrestling, actually) kicking a pro wrestler into a fire.
According to Barney, Arnold Schwarzenegger's character, Trench, wanted to be the President. In the 2007 film The Simpsons Movie, there is a President Arnold Schwarzenegger.
I Am Not Leonard Nimoy: The titular Expendables, not that we're complaining; it's pretty much why we watched it.
Most Wonderful Sound: In the first two films, Hale Caesar's AA-12 produces an immensely satisfying "THUNK THUNK THUNK" sound that signals someone turning into hamburger.
Also the close-up of Ross stabbing one of the mooks who were going to rape Sandra. Doubles as Special Effects Failure as the blood looks rather off in the shot and his knife kinda wobbles around unnaturally.
Gunnar's taunt towards Yin Yang is pretty cheesy: "What do you wear, size three? Bring it, Happy Feet!"
The CGI blood, which led to a lot of mockery from detractors and even some of the film's fans.
Romantic Plot Tumor: The subplot of Lee's pining for Lacy and his bemoaning about being unable to get together with her because of his job as a mercenary which took up a good chunk of the first film.
Cracked claimed in its article that the film is an adaptation of the 1978 film The Wild Geese, which was actually based on an unpublished novel by Daniel Carney called The Thin White Line, which later got republished after the film's success.
Some compared it to Jagged Alliance, especially Jagged Alliance 2 due to having a story having mercenaries being involved in aiding the resistance in a South American country along with the action movie tone.
They Wasted a Perfectly Good Character: General Garza's twin bodyguards. What's the use of having two star MMA fighters like Antonio Rodrigo and Antonio Rogerio Nogueira in a film filled with many other fighters and martial arts experts if you don't work any hand-to-hand fight scene with them?
Steve Austin is famously talented on a microphone. How many lines did he have again?
Took the Bad Film Seriously: Many critics who didn't like the movie were nevertheless impressed by Mickey Rourke's performance and wondered what such a dedicated performance was doing in a "brain-dead action flick". Oddly enough, a lot of critics, in a doubly inverted version of this trope, were expecting slam-bang action all the way through, but complained about the overuse of CGI (which was not a staple in 80s movies), the too-modern Shaky Cam, and, most unexpectedly, it having too much plot.