5. Why did Vince leave his gun on the counter at Butch’s apartment when he went to the bathroom?
Quite simply, he didn’t, the gun belonged to Marsellus. Vince was clearly with somebody else at the apartment as he didn’t react when Butch came in, thinking it was his partner. Jules had given up ‘the life’ by this point and Marsellus was probably filling in on this job. For further evidence look at the scene where Butch runs Marsellus over; the ‘big man’ is carrying two cups and as he is near to Butch’s apartment, we can assume that he is Vince’s partner.8. What was the book that Vince was reading on the toilet?
“Modesty Blaise”, a pulpy novel written by Peter O’Donnell in 1965 which is very much in keeping with the film’s title.
The film opens in a diner as a couple of thieves discuss the possibility of holding up restaurants. This leads us into three distinct strands; a date between a hit man and the wife of his boss, the boxer who is supposed to throw a fight and the cleaning up of a hit man’s mistake. The stories are told in non chronological order and we finally return to the diner for the final scene.
http://www.godamongdirectors.com/tarantino/faq/Quentin_FAQ.html#Pulp_Fiction