I'm pretty sure that alliteration is primarily defined as when the words start with the same *sound* as each other - not necessarily the same letter. Thus I would question "Tropic Thunder". For lack of an actual illustrative example of the opposite case, the fictional movie I just made up in my own mind, "Phil, the Filandering Feline" *would* be alliterative, despite the words not starting with the same letter.
What? "Breeze" and "blew" both start with the b-sound. The fact that the SECOND sound differs is irrelevant. And "foam" and "flew" both start with the same identical f-sound.
I’m hereby nominating Robert Downey Junior as the King of the alliterative movie title:
Tuff Turf (1985), Air America (1990), Home for the Holidays (1995), Charlie: The Life and Art of Charles Chaplin (2003), Good Night and Good Luck (2005), Due Date (2010) Avengers: Age of Ultron (2015) and a brilliant double whammy: Kiss Kiss Bang Bang (2005). A lot of multiples of 5 there. Maybe next year he’ll do a remake of the classic Dr Seuss story, “Horton hears a Who?”
Sean Connery and "F," or Tom Cruise and "W" would both be good substitutes.
A frequently-quoted example is from Coleridge's "The Rime of the Ancient Mariner":
“The fair breeze blew, the white foam flew,
The furrow followed free;
We were the first that ever burst
Into that silent sea.”
Note that "breeze blew" and "foam flew" start with the same letter, though not exactly the same initial sound. Still counts as alliteration.
Tuff Turf (1985), Air America (1990), Home for the Holidays (1995), Charlie: The Life and Art of Charles Chaplin (2003), Good Night and Good Luck (2005), Due Date (2010) Avengers: Age of Ultron (2015) and a brilliant double whammy: Kiss Kiss Bang Bang (2005). A lot of multiples of 5 there. Maybe next year he’ll do a remake of the classic Dr Seuss story, “Horton hears a Who?”