Question: What was the point of Jamal explaining the cost of pani puri? Did he really not know the answer to the simple question?
Answer: I believe it was to demonstrate that as a "slumdog" he knew some things but not others. He obviously did not know the answer to the question asked on the game show that the police chief asks him about, so to defend himself, he proves that he DOES know some things: just things that not everyone knows.
Question: Does anyone else think it strange that we don't see a crucial scene with Jamal applying to be on the show, but just a passing reference to the fact that he knew exactly when you would need to dial in? All I saw was the conversation with the Scottish woman. Did I miss something? Was this bit cut?
Answer: We are told (and shown) that Latika watches Who Wants to Be a Millionaire and Jamal's co-workers talk about getting on the show so he knows how to do it. Additional information is given in a deleted scene on the DVD.
Question: Why, at the end of the film, doesn't Jamal simply call Latika on the mobile phone instead of hanging around the station looking desperate the following day? (I assume the following day, since Latika has changed her clothes, although she took no spare clothes with her when she escaped).
Answer: Jamal never had Latika's phone number. The whole reason he found her at the end was because Latika had Salim's phone. Jamal called the number expecting to get Salim, but got Latika instead.
Question: Why does Salim sit in a bathtub surrounded by rupee notes of various denominations before shooting at the mob boss and getting shot in return?
Answer: People have said that it may possibly be a metaphor in that the rupees he is surrounded by is actually "blood money" that the mob bosses had amounted, and he was intent on staining the notes with his own blood. But there is no correct answer to this - it's something that you need to interpret for yourself.