Aamir Khan's character in both the films gives similar message to the parents of an ambitious child (dyslexic boy Ishan in TZP & his friend Farhan in 3i) i.e. to let their child follow his 'dream/passion' (viz. 'painting' in TZP and 'wildlife photography' in 3i)
the scene in TZP where Ishan gets lost in the crowd temporarily losing his mom's hand at a railway station is an homage to the scene where christian bale's character loses his mother's hand in the crowd while leaving their city during mid-war time