In period films what do you call a person who ensures that furniture, clothes, vehicles used are of that period in which the plot takes place. Can’t understand how Ambassador Mark IV figures in films set in 1956? How 1960 Fiat has a badging of Premier Padmini.
You see Mark 3 and Mark IV Ambassadors in Hindi film “Parineeta”? In Marathi film “Ani Kashinath Ghanekar the tail lamps of Ambassadors are Ulhasnagar fitmets. Tata bus is from 1980s. In ‘Raazi’ I think you see a Matador with a Firodia logo.
Ambassador is an evolution of Morris Oxford. Mark IV came much later in around 1980 with square shaped indicators & a toothy grille & it had extra amber indicators placed below the bumper. This is the minimum one should keep in mind when using Ambassadors cars in period films.
“Ani Dr.Kashinath Ghanekar” a biopic on Dr Kashinath Ghanekar a film which is set in 60s shows a Bajaj Chetak/Super ( don’t know which) with those amber side indicators which were introduced in 80s. (Zoom and see) 
The same film got the old “Dukar Fiat’ right but missed avoiding the white Premier Padmini in the background which came in 1980s. The air vents/dam which was introduced on Premier Padmini only on some ‘Deluxe’ and ‘Deluxe-BE’ in 90s models can be seen above the bumper.
‘Attacks of 26/11’ a movie set in 2008 shows Mahindra XUV 500 parked outside Leopold Cafe in Mumbai when XUV 500 was launched somewhere in 2011.
The film ‘Special 26’ set in around 1984 had accurate representations. They used cars like the old Maruti 800, Old Ambassadors, the hoardings of soft drink ‘Thril’, magazines with Karen Lunel ads of Liril. They even had a news readers dressed to resemble Salma Sultan and JB Raman
