Well, the Phoenix used two types of Titan missiles, depending on which shot, and there's notable differences between the two, unfortunately.
Well, not really, AFAIK. The full-scale "prop" was a real Titan II ICBM, and only its upper works were seen sitting in the museum silo they used for filming. The flying model was a totally fictional missile that some sources have dubbed Titan V (no relation to the real space launcher of that name whatsoever), and in terms of appearance this differed from the real ICBM only by having a single futuristic nozzle at the bottom, rather than the two engine bells of the real thing. So essentially the "prop" and the model were identical for all of their visible parts.
Of course, the real Titan II of 1950s design philosophy and 1960s-1970s execution was struggling to reach an orbital trajectory for its minuscule Gemini payload by using its two stages (it had been designed to loft a similar mass of nuclear warheads for a ballistic hop), while the lower stage of this fictional Titan V alone easily achieved escape velocity for a gigantic spacecraft the size of the entire upper stage, propelling it farther away from Earth than any real-world single rocket stage has ever done.
Here's a random shot of a Titan II (with nuclear rather than Gemini spacecraft payload), with her engines and the shape of the nose cone essentially the only things not in common with "Titan V":