Rani Mukerji and Aishwarya Rai Bachchan were best friends in the industry until Aishwarya Rai was dropped out of the film, and Rani took up the role. Despite Aishwarya's marriage to Abhishek Bachchan, who is also good friends with Rani, they have not made up at all.
During Raj and Priya's visit to Mykonos, all the sites shown (Lykabetos Hill, Vouliagmeni Cave, St. Constantine Square, Faliro Luna Park etc.) are in or near Athens. Only the windmill dance sequence was in fact filmed in Mykonos.
Raj (Shah Rukh Khan) couldn't drive to Athens if an airplane couldn't get to Athens due to bad weather. Also there was no sign of bad weather on their way to Athens.