Kangana Ranaut's character was based on X-Men's Mystique and Vivek Oberoi character was based on X-Men's Magneto
Around 600 Krrish masks were used during the filming of the movie; since they are made of wax, they tend to melt. Hrithik Roshan thus had to do more rounds of set.
Hrithik Roshan was impressed by actress Chitrangda Singh, was once attached with the film, she even took kick-boxing lessons for the role, but later she was replaced.
Third installment of the Dhoom franchise was also released the same year. In 2006, the second installments of both Dhoom and Krrish franchises were released both starring Hrithik Roshan.
Director Rakeysh Omprakash Mehra was slated for directing this sequel when it was planned for 2010 release, but later replaced by original director Rakesh Roshan due to 'development hell'.