Many of Stack's narrative segments were filmed at the Pasadena Masonic Temple. The old-fashioned exterior "suggested ghostly spirits" to the producers.
Stack once said he viewed his narrative role as something like the stage manager in Our Town.
Robert Stack had an "Unexplained" event in his own life. A very private person, he would never fully disclose details, but it may have had something to do with his mother. He was known to believe in an afterlife and in Ernest Holmes' Science of Mind philosophy. He did many segments on Catholic miracles including Lourdes and Fatima. He was of Italian heritage on his mother's side and may well have remained a Catholic.
Corpsing: Robert Stack is clearly trying not to laugh while discussing the bank robber, nicknamed "Fumbles".
For the segment on the disappearance (and possible murder) of Jeremy Bright, one of Jeremy's friends Cecelia Fish appears in an interview, telling of an incident where a strange man showed up in the lobby of her apartment building covered in blood. Cecelia mentions being frightened of this man, but the actress playing her in the re-enactment can clearly be seen smirking, and holding back laughter when the man comes sauntering in with blood on him.
The case of Andre Jones had the mother of the man, in the original broadcast, say that someone in the jail he was held in claim that police had referred to him by a derogatory term. In subsequent airings of the segment, the offensive word is blanked out.
The case of the late Reggie White's church vandalism and bombing had racial epithets written on the wall which were completely censored in the Spike TV airings.
In the Rachel Timmerman case, when recreating the scene when her body was discovered, initially the actress was portrayed as nude, like Timmerman was when she was found (albeit from a distance away). Later airings had the woman's barely visible nudity as blurred out.
Terri McClure was murdered via a Boom, Headshot! and was depicted as being found sitting upright in her car. Airings in syndication have completely obscured the gruesome sight of her bloody head.
Similarly, the gruesome death of Captain Jeffrey Digman (which is in all likelihood a homicide) shows the crime scene photo of his body, but later airings would blur out his blood-covered head/face.
Gratuitous Special Effects: In the episode showing the Beatrice, Nebraska West Side Baptist Church explosion, they used a real church scheduled for demolition. The special effects expert got too enthusiastic and used 95 sticks of dynamite plus 30 gallons of gasoline, creating a massive explosion and fireball. Fortunately, the film crew had put wooden crates around the cameras and they were protected.
Keep Circulating the Tapes: Averted, now for the majority of the series. Much to the delight of fans, the original Robert Stack episodes of Unsolved Mysteries were finally made available for streaming, uploaded to Hulu and Amazon Prime. It's also on Pluto TV on continuous. However, several segments are missing due to legal reasons or not being able to have the segment restored. Missing segments include the Orange Sock murders, Mike Riemer/Diana Robertson, Luis Diaz, Dave Davis, the entire short-lived Final Appeal series, and more. The only way to ever see these segments are if anyone uploads old recordings on the Internet.
The "Tallman's Ghost" segment (better known as the Haunted Bunk Bed segment) is absent from streaming, though it was included on the now out of print "Ghosts" DVD set.
Some missing persons segments that are basically unsolvable at this point have been left off the Amazon Prime package. One example would be the George Owens segment, featuring the story of an elderly man who was 80 years old when he vanished in 1985 and would be 114 today. Given that all the subjects interviewed in the segment have long since passed away and that George is most certainly dead at this point, the story has been withheld from release.
After years of segments being removed from YouTube for copyright violations, since February/March 2019, the show has its own YouTube channel, thanks to Film-Rise, with every original episode from its first run uploaded, complete with updates when available— for free!
Name's the Same: Of a 1930's radio show, which also featured crime stories.
New advances in DNA testing ended up solving some of the mysteries such as identifying murder victims, unknown dead people and even wanted criminals.
Some of the cases featured on the show might have been solved nowadays with recent advances in technology. Take the nightmarish case of Bill and Dorothy Wacker. They were harassed and stalked for years by an unknown assailant or assailants. Had this happened today in the 21st century, things may have been different. For example, caller ID is a standard feature on phones and may have made it easier to identify their stalker. Also, digital camera technology has made said devices cheaper and smaller; hidden cameras might have ended up catching the face of their stalker. The same goes for poor Cindy James, whose assailant was almost certainly Dr. James Tyhurst, a colleague of Cindy's ex-husband. Convicted in 1991, two years after Cindy's death, of sexually enslaving and brutalizing four of his patients in a similar fashion, he managed to get the case overturned on appeal. He is still out there.
Unintentional Period Piece: The heavily synthesized music and the graphics used in the various introductions are hopelessly stuck in the 80's/early 90's, but arguably not to the show's detriment. The fashions and attitudes in the cases themselves are also obviously of their time, especially the younger men and women with '80s Hair.
The show treated the paranormal segments with as much reverence and seriousness as they did for any other category. As functionalist "skepticism" note a real skeptic is someone undecided and seeking more information has become more popular into the 2010s and 20s, many present-day viewers may find these segments more silly than scary or compelling. This is a real YMMV, as plenty of viewers still contribute to message boards talking about enjoying the paranormal stories, and there are special DVD box sets devoted exclusively to them.
Word of God: Some family members of those involved in certain segments have stated online the outcome of some mysteries that weren't revealed during the Dennis Farina era of the show. For example, Jenny Pratt's sister revealed that Jenny's attacker (who left her with brain damage) was eventually found, but unfortunately, he committed suicide before he could be brought to justice.