There are a surprising number of these, if I'm remembering correctly.
"Twenty Two" (S2:E17) was based on "The Bus-Conductor," which was previously filmed in
Dead of Night (1944), though I think the
TZ version is eerier and better.
Several of the other "evil dummy" episodes ("The Dummy," "Caesar and Me") are based on another great segment in that movie, the "Ventriloquist's Dummy" sequence.
"Queen of the Nile" (5:23) borrows a great deal from
Sunset Boulevard.
"
King Nine Will Not Return" (2:1) was based on the real-life disappearance of the
Lady Be Good in 1943, an incident which was previously fictionalized in February 1960 (just a few months before the TZ episode) as "Ghost Bomber" on
Armstrong Circle Theatre. It would later be fictionalized as the telefilm
Sole Survivor in 1970 (
Sole Survivor being, of course, the answer to the famous "what is my movie?" question on the old boards).