Romance of the Rails - 1912 was released on:
USA: 5 November 1912
Koko Hot After It - 1926 was released on: USA: July 1926
Hot Package - 2012 was released on: USA: 31 March 2012
Hot Sports - 1929 was released on: USA: 11 August 1929
Hot Paprika - 1935 was released on: USA: 12 December 1935
Hot Dog - 1932 was released on: USA: 20 February 1932
Koko Hot After It - 1926 was released on: USA: July 1926
Hot Dog - 1926 was released on: USA: 8 February 1926
Hot Cakes for Two - 1926 was released on: USA: 17 January 1926
Red Hot Hoofs - 1926 was released on: USA: 19 December 1926
They are there to allow for the expansion of the rails during hot weather.
Railroad tracks can bend when they get hot. Train tracks have a small gap where one rail meets the next rail. These are called expansion joints. When it is hot the rails expand making the gap smaller, and when it is cold the rails contract making the joints wider. If the expansion joints are not wide enough and the rail gets hot enough it will expand more than the expansion joint can handle and the rails can buckle. In other situations the rails can get what are called sun kinks and the rails actually bend out of alignment.
The gap is there to prevent the rails expanding and buckling during very hot weather.
Hot Dog - 1926 is rated/received certificates of: USA:Passed (National Board of Review)
Hot Date - 2009 was released on: USA: 2009
Hot Hippo - 1990 was released on: USA: 1990
Hot and Nasty - 1972 was released on: USA: 1972
Hot Midnight - 2014 was released on: USA: 2014