Unlike many modern devices, the robots in Real Steel are not connected to a larger network, rather they are operated by wireless devices. Lack of connectivity to a larger network limits their vulnerability to being hacked. It means some of the common cyberattacks like denial-of-service attacks are not capable of being done because of this lack of connectivity.
However, the wireless devices used to control the robots in Real Steel are still susceptible to many vulnerabilities, but the movie does not have any cases of hacking or malicious interference of robots. One of the possible vulnerabilities that could be exploited in these devices without could be a network vulnerability [1]. Without security measures, "robotic systems are vulnerable to various wired/wireless communication and connections attacks including replay, man-in-the-middle, eavesdropping, sniffing, spoofing, etc." [1]. Wireless jamming is another threat from which the robots could possibly suffer from [1]. This would completely disrupt the connection between the robot and the controller, possibly leading to rigged fights in the world of robot boxing.
In reality, any device that communicates wirelessly can be vulnerable to exploitation, but the film never mentions robots suffering any security risks.
References:
Jean-Paul A. Yaacoub, Hassan N. Noura, Ola Salman & Ali Chehab. Robotics cyber security: vulnerabilities, attacks, countermeasures, and recommendations. (PubMed Central, 2021). Robotics cyber security: vulnerabilities, attacks, countermeasures, and recommendations - PMC (nih.gov) Accessed 10 October 2024.