In the scene where Starsky, Hutch, Dobey and Captain Ryan realise who is behind the S&H impostors, on Starksy's line "Oh my God. I just spoke to her and asked her for immunity for Judith Coppet", the dialogue at the end of the sentence, "...for Judith Coppet", is VERY noticeably re-dubbed in post-production; the way the line suddenly cuts from the original recording to the overdub is noticeable even to the most casual of viewer.
(Quite why the end of the line was redone is anyone's guess; probably due to background noise interference).
With the doppelganger Starsky and Hutch driving around in an identical Ford Torino to Starsky's, an extra Torino was needed for the production of this episode (at least three were used during filming the story). But one of the Torinos doesn't quite match the other(s). The most noticeable difference (especially for non-car enthusiasts) is that the back section of the white stripe, which it curves up towards the roof, is angular, not the usual rounded stripe. The extra car is also sitting lower on its suspension than the 'jacked-up' regular version, and instead of the 'Appliance brand' slotted dish rims on the TV car(s), this one has 'Keystone Klassics', a totally different style of wheel. Plus, this car has raised white letter tires, and the regular TV cars were always blackwalls.
The different car (identifiable by the 'angular stripe') can be spotted at various points through the episode; changing to the regular-version Torino and back again between different shots for both Starsky and Hutch, and their impostors' scenes! When (the real) S & H get the call to go the massage parlour it can clearly be seen, and can it again when the fake S & H are getting out of theirs a few minutes later. It's also prominent during the chase at the climax, but again flips back and forth between shots!
It's quite feasible that the fake Starsky and Hutch's car wouldn't be exactly identical to the original, but the fact that the real Starsky's genuine model is also seen to suddenly flip versions is less forgivable!
In the first scene with (the real) Starsky and Hutch in, at the Police station, as they enter the office watch the reflection in the window pane as Hutch pushes open the door – there's a flash of light. A freeze-frame reveals the source to be the reflection of two of the lights used to light the scene.
There must not have been enough mag wheels to 'dress' both Torinos used in this episode. One of them has a standard-issue steel wheel on the front drivers side that has been painted silver to try (not very successfully) to resemble the mags that are normally used. The only problem is that the steel wheel keeps jumping back and forth from the 'real' Torino to the 'fake' Torino for the entire episode!
Starsky is trying to talk Hutch into a blind double-date -
Starsky: "Do you trust me or not?"
Hutch: "With my life: yes. With you're choice of women: No"
This is the last episode to use Mark Snow's classic, definitive theme, the one most recognised and most associated with the series – somewhat surprisingly, it was replaced with another theme for the third season. Thankfully, the beloved second season theme returned, in a re-worked form, for the fourth season.
Hutch's evil doppleganger, Hanson, is portrayed by Gary Epper, David Soul's stunt-double on the series.