After the murder of Mahesh Saxena, who is killed on the 1st of January, the inspector says that he met Saxena on the 'Chautha' of Kailash Chopra, who was killed on the 29th. However, Chautha is four days after death, which cannot happen between the 29th and the 1st.
When Ajay Devgn goes to Four Fox company, they speak about a CD and copying of a CD while the film is set in 1992 (12 years before) when CDs were not available.
When Mukesh Tiwari is being chased by Taarzan The Wonder Car, he puts the right indicator but wants to go on the left side of the road.
When Deepak Shirke's jeep overturns you can make out no one is in the jeep.
Ajay Devgn says that the toy Tarzan figure that he hangs in his car is from his childhood. Since the toy is based on the 1999 Disney animated "Tarzan", it is not possible for Devgan to have the toy in his childhood or even in his adulthood (which was set in 1994).