Rahul takes the urn from his house and keeps in his bag. Later at the railway station, his grandmother hands it to him again.
Rahul's Grandfather is watching a one-day cricket match between India and Pakistan in 2013 and Sachin Tendulker is batting. Sachin Tendulker retired from one-day cricket in 2012.
The train number of Chennai express as shown in the movie when Shahrukh boards the train is 11028 which actually is for Mumbai mail. The actual number of Chennai Express train is 12163.
Just before getting down from the train to Deepika's village (Khamman) Sharhrukh and Deepika are shown in Sleeper Class (SL) Coach.
When they get down, they get down from General (II) Class coach.
In India General coach are not joint thus there is no way you can go from one coach to other.
When Rahul introduce his GrandFather, he says that his grandfather is a hardcore fan of Sachin Tendulkar and shows him shouting 'Sixer!' at Tendulkar's six in his 2009 Indian Cricket Jersey i.e Dark Blue Jersey. After some years, i.e, while celebrating his 100th Birthay, we saw him watching the live match of India vs Pakistan, where Tendulkar is in his 2007 Indian Cricket Jersey, i.e, sky blue jersey.
When Deepika's claims that her village Khammam(which as per her is supposed to be in Southern part of India) is arrived, it is actually Dhudhsagar Falls, which is a scenic beauty near Goa/Maharashtra/Karnataka Border. It is no where close to Chennai.
When Rahul and Meena heads for Rameshwaram, they are shown to actually to go in the opposite direction with the Pamban bridge on the right. Again, a while later when they are shown to go back from Rameshwaram, it was again in the opposite direction.
When his ticket is checked on the Chennai Express, Rahul has a ticket to Chennai. He did not buy a ticket from Kalyan to Chennai.
When the Marine Police bring Rahul back to Komban Village, Meenamma's 2 brothers: Chinna and Periya speak to the Police and Rahul in Hindi. Hence they should have also understood the Hindi song-conversation between Rahul and Meenamma in the train.