The title track song 'Bachna Ae Haseeno', was sung originally by Kishore Kumar in the film Hum Kisise Kum Naheen (1977)and was filmed on actor Rishi Kapoor. When the idea about using the song 'Bachna Ae Haseeno' from the old movie came, the music duo Vishal Dadlani and Shekhar Ravjiani were excited but they decided not to do a remix version of it. The track was completely re-worked by retaining some of the original vocals of Kishore Kumar on the beginning of the song. And then they got Kishore Kumar's son Sumeet Kumar to sing the rest of the song as a new composition with Vishal Dadlani's rap lyrics. The final product turned out to be unique mix with the legendary singer Kishore Kumar and his son heard in one single track in which the recording is separated by decades and that same song filmed on actor Rishi Kapoor's son Ranbir Kapoor.
Since two of the film's characters work for Microsoft Game Studios, plenty of video games that have been released by the studio are referenced. In addition, nearly all of the movies referenced are previous releases from Yash Raj Films, with the notable exception of Hum Kisise Kum Naheen (1977).
Raj works at Microsoft in Sydney as a game developer who made Halo 3. But Microsoft was just the publisher of Halo 3. Halo 3 was developed by Bungie Studios.
As Mahi and Raj sample the chocolates in the Swiss candy shop the chocolates at the corners where the shop keeper takes the samples from keeps getting replaced when the camera angles change.
While playing in Swiss Alps, Ranbir and his friends are heard singing "Dhoom Machale". The story in this movie revolves around 1996 and Dhoom wasn't released until 2004. However, background music is rarely dictated by which time period the film is in.
Raj Sharma: Actually, I am impressed... at three in the night... alone, being a beautiful Indian girl... you're driving a taxi in Sydney. Aren't you scared?
Raj Sharma: [In Hindi]
Love. Affection. Fondness. Passion. Whenever it happens with someone, it changes one's life, the heart starts beating faster and makes you sigh. It gives you sleepless nights, one tends to daydream, it teaches you what it means to love someone. It teaches you how to take those seven steps, which lead to the journey of seven lives. If you're lucky, you find your love, in just one shot. My case is different. I am a killer. I found this love three times.
Raj Sharma: [In Hindi]
A very killer philosopher had said, that the past is over, there is no control over it. And you'll rectify the future only when you set things straight in the present. Hello. I had said that. Wow. I am a killer.