According to director S. Shankar he originally written movie for Kamal Haasan, and they even made a photo shoot for the promotion of the movie. The film was originally planned in 2001, and was to star Kamal Haasan and Preity Zinta.
In July 2007, Shah Rukh Khan was signed on to be the male lead of Chitthi as well as the producer of the film. However, in October 2007, Shah Rukh Khan and Shankar officially called off the project. Khan commented that the script was "half-baked" and "dull" in comparison to his other films at the time.
Depictions of cobras serve as a lucky mascot in Rajinikanth's films. Nearly all of his films featuring them in one form or another become either top-grossing films or commercially successful films at the box-office. In this film, one of the formations of Chitti's CR-army of robots in the climax fight is a giant cobra.
Rajinikanth's following film after Enthiran was 'Kochadaiiyaan' (2014), which was India's first full motion-capture animated film. However, 'Enthiran' was the first time Rajinikanth performed via motion capture. This was for a few parts as Chitti, notably the robot's first attempt at walking near the beginning of the film (where he mimics the walking style of his creator Dr. Vaseegaran, also played by Rajinikanth), and the robot-giant formation near the end of the climax fight.
In December 2008, Eros International withdrew from funding the project after financial difficulties caused by the box-office failure of Drona (2008) and Yuvvraaj (2008), with the subsequent departure of Ayngaran International, which struggled with the global financial crisis of 2007-08.
In an interview with the Tamil channel Sun TV, held shortly after the film's release in October 2010, Rajinikanth revealed that Shankar, following the release of his Indian in 1996, had approached and pitched three storylines for him to consider for his next venture.
After rejecting Ramoji Film City for technical reasons, Enthiran's producer, Kalanithi Maran, took six months to set up three air-conditioned studio floors on land in Perungudi owned by Sun TV Network.
The filming for Chitti's introduction to the international robotics conference was completed in December 2008 at Sri Sivasubramaniya Nadar College of Engineering and Vellore Institute of Technology, where more than 400 students were used as extras.
Sabu Cyril told Uma Kannan of The New Indian Express that the sets for the climax sequence, which was filmed at Mayajaal, consisted of a tar road and glass buildings which rose to 65 feet (20 m), and that aluminium composite panels, reported to have cost INR50 million, were also used to design the sets.
D'Souza incorporated the popping style of street dances in "Irumbile Oru Irudhaiyam", but encountered difficulties in performing the dance movements in tandem with the robot, and with the restrictions created by the rigid costumes.
Both Mohan and Shankar visited several visual effects companies, including the New Zealand-based Weta Digital and the United States-based Industrial Light & Magic, Cafe FX and Tippett Studio before partnering with Legacy Effects.
After a series of previsualisation tests, including a scene in which Chitti jumps on a train to save Sana, Mohan eventually decided to use the technique in 40 out of the 60 visual effects scenes featured in the film, consisting of 2,000 takes.
To create the robots with Rajinikanth's appearance, a complete scan of his face in 3D digital format in all possible lighting conditions was conducted using the Doom Light Stage, so that his face could be replicated on the mannequins.
Despite Shankar's claim that Enthiran was a purely original idea, it has been compared to Mary Shelley's 1818 novel "Frankenstein", owing to the similar personae of Chitti and Frankenstein's monster, both of which turn against their respective creators.
K. Moti Gokulsing and Wimal Dissanayake, in their book Routledge Handbook of Indian Cinemas, noted the similarity between the film and "Frankenstein", arguing that Chitti was "manipulated by Bohra to become a Frankenstein-like figure".
Director and film critic Sudhish Kamath called Enthiran "a superhero film, a sci-fi adventure, a triangular love story with a hint of the Ramayana", while remarking that Enthiran's similarities to The "Terminator" (1984) were "more than obvious.
Although Shankar initially claimed that Enthiran would be made for all audiences, including those lacking computer literacy, the film is influenced by and makes references to many scientific principles relating to the fields of engineering, computer science and robotics, including terabytes and Asimov's laws of robotics.
In his book "Visual Perception and Cultural Memory: Typecast and Typecast(e)ing in Malayalam Cinema", Sujith Kumar Parayil notes the similarities between Kalabhavan Mani's role in the film to the one Mani played in the Malayalam film "Sallapam" (1996).
For the soundtrack and score, A. R. Rahman made use of the Continuum Fingerboard, an instrument he had experimented with previously in the song "Rehna Tu" from Rakeysh Omprakash Mehra's drama film "Delhi-6" (2009).
The film was released in 2,250 theatres worldwide, including 500 theatres in Tamil Nadu, 350 theatres in Andhra Pradesh, 128 theatres in Kerala, 23 theatres in Karnataka, and 750 theatres in North India.
Novelist Aarur Thamizhnadan demanded INR10 million from the director and producers for plagiarism and filed a case against Kalanithi Maran. In June 2011, the Madras High Court dismissed the case after a petition filed by Maran denying the allegation was approved.
Box Office India estimated that Enthiran netted INR1.95 billion across India with the Tamil version netting INR1.20 billion, the Telugu version netting INR530 million and the Hindi version netting INR220 million.
In a personal appreciation letter to Shankar following the film's release, the director K. Balachander described Shankar as India's James Cameron, "Enthiran" as India's "Avatar" (2009) and Sun Pictures as India's Metro-Goldwyn-Mayer.
In the film, Chitti often introduces himself by stating the clock rate of his central processing unit, which is 1 terahertz (1012 hertz), and his random-access memory limit, which is 1 zettabyte (1021 bytes). This introduction dialogue, which is spoken by Chitti as "Hi, I'm Chitti, speed 1 terahertz, memory 1 zettabyte" became popular.
Joe Leydon of Variety believed that Shankar "riffs on everything" from Frankenstein to The Terminator, but suggested that the film was an "overwhelming mash-up of American-style, f/x-driven sci-fi spectacle and a Bollywood musical."
Scenes from the film, particularly one known as the "Black Sheep" scene, have been parodied in subsequent films, including "Mankatha" (2011), "Osthe" (2011), "Singam II" (2013), as well as in the Telugu films "Dookudu" (2011) and "Nuvva Nena" (2011).
On Rajinikanth's 64th birthday, an agency named Minimal Kollywood Posters designed posters of Rajinikanth's films, in which the Minion characters from the "Despicable Me" franchise are dressed as Rajinikanth. The digital art was hand drawn on a digital pad by Gautham Raj. One of the posters depicted a mutated Minion, reminiscent of Chitti's "villain robot" look in Enthiran.
Co-hosted by Vivek and Punnagai Poo Gheetha, the music launch event was attended by most of the film's cast and crew members, including Kalanithi Maran, S. Shankar, Rajinikanth, Aishwarya Rai, A. R. Rahman, Santhanam, Karunas, Vairamuthu, R. Rathnavelu, Anthony, Sabu Cyril, and Yogi B. Other invited guests were Dayanidhi Maran, Radha Ravi, Vadivelu, Shriya Saran, Jayam Ravi, Ramya Krishnan, S. A. Chandrasekhar, Aishwarya and Soundarya Rajinikanth, Krish, and Sangeetha Arvind. Furthermore, Silambarasan, Vijayalakshmi, and Poorna were part of stage performances.
For shooting the song "Kilimanjaro" Machu Pechhu, there were interventions from the Indian government to grant permission for the filming, which was denied to many international projects, such as "Quantum of Solace" (2008).