Michigan was chosen to film this movie by director Shawn Levy because he was blown away by the Model T Automobile plant in Highland Park near Detroit. He felt it was the perfect set for the first fight scene called Crash Palace in the film. No other location he visited in New Mexico, Los Angeles, or Georgia came close.
In an obvious nod to the iconic game "Rock'em, Sock'em, Robots", during the Atom/Zeus fight, Mashido assumes manual control of Zeus and grabs two simple joysticks and moves them back and forth operating Zeus exactly as done in the board game.
As announced at the rodeo in the beginning of the movie, director Shawn Levy has confirmed that the film takes place in 2020. He stated in an interview: "The whole reason it's 2020 [and not further in the future] is because I knew this movie was going to be an underdog story and I didn't want the distant futurism of extreme sci-fi. I wanted the world to feel really familiar, so that the characters would feel really relatable. The cell-phone we used five or ten years ago looks different from today, but a diner still looks like a diner."
The movie references professional wrestler The Rock (Dwayne Johnson) as Ricky says at the beginning of the first fight in the movie, the one in the ranch, "...lay the smackdown", a typical catchphrase of the former. The robot is also declared "The People's Champion" at the end of the movie, one of The Rock's nicknames.
In the scene where Atom is about to enter the ring before fighting Zeus, Hugh Jackman (who has made public before his admiration for boxer Manny Pacquiao), was seen carrying a case for Atom's remote control (at 1:40:34 & 1:43:50). On that box was a sticker of the Philippine flag, the country where Pacquiao was born. (Another view of the case is at 1:20:43 just before Atom's fight with Twin Cities.)
In the sequence in the junkyard on the DVD director's commentary, Shawn Levy says "This was an aggregate plant. I don't even know what that means. All I can tell you is that it's a place, I think they made gravel, and what you'll notice is that I would say that 25% of the cranes and gantries and machinery that you see in this shot were there. The other 75% we either brought in or set-extended, like in this shot, digitally. But everything you're seeing here is real - we built the skeleton of a rocket, we built in the background of Hugh and Dakota, that husk of a USA rocket."
When Mashido makes his first appearance he is surrounded by reporters asking questions and shoving their microphones under his nose. One of these microphones (the light grey one on the left) bears the logo of the real-life Austrian/German TV station "Pro7".
In an apparent nod to WWE Legend Hulk Hogan, during his entry into the ring for the match against Atom the world champion robot "Zeus" mimics the 'signature' Hulk Hogan pose with his hands. (In the DVD commentary Shawn Levy mentions that Zeus' signature move is, unintentionally, exactly the same as the move by The Thinker in Night at the Museum: Battle of the Smithsonian which Levy also directed.)
Director Shawn Levy notes in the DVD commentary as the bull comes out of the chute to fight Ambush, that two bulls were used, but that the better performer, Kujo, only had one horn. In that shot, a second horn was added with Computer Graphics.
Although Max's guzzling Dr Pepper in the scenes at the Parkway Motel (at 1:05:47) might be suspected as product placement, Shawn Levy mentions in the DVD commentary (at 1:09:02) that the production only received permission to use Dr Pepper, without remuneration. The filmmakers wanted to use a recognizable product containing caffeine that could make Max hyper enough to have worked throughout the night.
The trivia items below may give away important plot points.
Among the many parallels to the movie Rocky, the world champion (Zeus) gives an unheralded local club fighter (Atom) a shot at the title and then unexpectedly gets into the fight of his life before winning a controversial split decision to the disdain of the crowd; the fight lasts the full 5 rounds with each fighter suffering many injuries; the match illustrates Atom's apparently unlimited ability to absorb punishment; and despite losing, Atom is declared "the people's champion."
Charlie Kenton's idea to wear down Zeus's power supply by allowing him to repeatedly land blows on Atom was in fact a technique used by real life professional boxer Muhammad Ali. Nicknamed the 'rope-a-dope', Ali utilized the strategy to tire fellow boxer George Foreman, a much stronger opponent than himself, and eventually gain victory. Ali famously angered Foreman with phrases such as "Is that all you got, George?" during the fight, mirrored in the film by Kenton's taunting hand gesture.