When Paris (under cover as Major Shen) hands Martillo a document to read, the title is "Psychiatric Personality Study - Juan Acero" and the first paragraph indicates Acero is a megalomaniac. But the second and third paragraphs are actually text copied from the short story "The Doctor's Son" by John O'Hara. The copied text starts "I noticed he did not sit down; he was actually a little taller than Edith..."
The helicopter Barney is assembling from parts is actually a Bell 47J-Ranger. It is also seen in "The Man from Uncle" and "Hawaii Five-0" to name a couple.
The Bell 47J helicopter bears the registration number N1142W which identifies it as the same helicopter that is seen in The Pink Jungle (1968)
Arthur Batanides appeared in the Star Trek episode, "That Which Survives", but shared no scenes with Leonard Nimoy.