A search to find extra material online for TV shows and movies...
Maybe it's the completist in me, may be it's the person who is interested in how films develop, but, here are 10 examples of short films that later became full length features...
Bottle Rocket (1996) - Bottle Rocket (1994).
Cashback (2006) - Cashback (2009): The short film is "absorbed" by the feature becoming part of the bigger film.
Cube (1997) - Elevated (1997): A short film made as "proof of concept" to get investors for the feature.
DEBS (2004) - DEBS (2003)
District 9 (2009) - Alive in Joberg (2005).
Napoleon Dynamite (2004) - Peluca (2002)
9 (2009) - 9 (2005).
This is the End (2013) - Seth & Jay vs the Apocalypse (2007).
THX 1138 (1971) - Electronic Labyrinth THX1138 4EB (1967).
12 Monkeys - La Jetée (1961): The credits of 12 Monkeys say it was inspired by La Jetée but the basic idea and plot is drawn from the short (although the short is in a very different style).