Use of British/American English: "Initialising" in the flashback with Rohit, and "Initializing" when Dr Arya uses the computer.
Priya's belt disappears for a moment when she runs towards Sonia as the kids gang up with Krishna to play a joke on her.
Honey says she was away for 2 seconds after the scene where Krishna fixes Priya's foot, but the scene itself lasts more than 10 seconds.
At the circus, when the tanks explode, Priya's camera falls off her hand to the ground. However, during Krishna's wardrobe makeover, the camera is seen "conveniently" placed next to unconscious Priya's hand.
The computer that Rohit Mehra invents is coded with a password that is Rohit's retina and heartbeat. Scientists which could analyze his research to the extent that they completely rebuild the whole computer would realize how he encoded those in the computer, ultimately not needing those at all. Also, the new computer would not have those two things as code anyway; it would simply be without any code.
Some of Krishna's actions shown in the movie are impossible, like his climbing the mountain in a zigzag fashion, simply because of the protruding walls of the mountain which would come in his way. Another example is cracking a rock with a volleyball.
There is a time-line inaccuracy in last scene, when Dr. Arya shoots two bullets at Rohit and Priya, who are standing about 20 feet away. No human can change a pistol's target immediately after shooting one shot and trigger a second shot before the first bullet hits a target that is just 20 feet away.
One of the thugs who attack Krrish the second time speaks with Kristian's voice.
The first super computer that Rohit Mehra invents is visually different from the super computer that is reinvented based on the first one. Keyboard of first super computer rests on a metallic stand where as later one appears as it is simply floating in air. The first super computer is operated by left hand where as later super computer is operated by right hand.
Priyanka and her friend decide to invite Krishna to Singapore to save their foundering jobs, and the next day he is actually in Singapore. How did they arrange the passport and visa in a single day?
Rohit is in Singapore for two years working on a secret project. Once two years have passed, his mother calls him up to say that his wife has given birth to a baby boy. He was away from home for two years so how did Rohit impregnate his wife?
When Dr Arya realizes that the Masked Man is still alive, he could simply see his real identity with the computer, when Krishna reveals himself to the dying Arya.
If the Singaporeans don't speak Hindi, how are they able to understand the Indians perfectly when they speak Hindi to each other?