When Gayatri rejects Raj's wedding proposal, he goes through a flashback of how he had betrayed Mahi and Radhika before. In the flashback, he sees Radhika crying at the place where they were supposed to meet for their wedding. He was already on a flight to Sydney when that happened.
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.