Solvers should connect the chains with actors common to the movies on either side, filling in the empty boxes. The movies with numbers in their titles should be placed on the tiles with that number. The finished grid is shown below (12 Monkeys can be replaced by 12 Years a Slave):
Apollo 13
Beyond All Boundaries
12 Monkeys
Fantastic 4
Deadpool & Wolverine
IF
GI Joe
Hail, Caesar!
Ocean's Eleven
Killers Anonymous
The Fifth Element
Three Billboards
10 Things I Hate
Clueless
8 Mile
Avengers: Infinity War
The Sixth Sense
Paradise Road
The Bourne Identity
Ghostbusters: Afterlife
Red Lights
Se7en
Changing Lanes
The Two Towers (Extended Edition)
Elysium
District 9
Oldboy
Paradise Highway
In My Country
North Country
Conan the Barbarian
Twins
One Flew Over the Cuckoo's Nest
Easy Rider
Sleepwalking
Reading the first letters of the movies in the grey squares gives the clue phrase BIG CAT PRINCE. This refers to the movie THE LION KING, which is the missing movie in the bottom-left corner (via James Earl Jones to Conan the Barbarian) and the answer to this puzzle.