The super hit song 'jaati hoon mein" was actually an rejected tune, rajesh roshan found it as not perfect & incomplete song. Rakesh roshan was working out the songs of karan arjun, he saw a box full of rejected tunes, he insisted to hear those tunes, he liked the tune 'jaati hoon main' and he told he told his brother to record that song which he thought will be a big hit, rajesh refused as the song was not perfect, but had to record it as rakesh insisted. When the song was released it was a big hit, but still rajesh roshan was unsatisfied with this song.
The movie was originally entitled "Kaynaat". Ajay Devgn was the first choice of Karan (Salman Khan).
The movie was initially titled Karna-Yudhisthira to showcase eternal bonded love of brothers just like Subhash Ghai's Ram Lakhan(1989) but the makers realised the duo were like Ram-Bharat and hence was controversial. Then it was changed to Karan-Bhima, then Karna-Krishna was almost finalised but then Rajat advised it for Karna-Arjun
Karishma Kapoor rejected the role, that Mamta Kulkarni eventually played.