Factual error: A character in the episode has invented denim, but denim was invented in 1873 and was being used widely up to the time period of the series, which is set in 1893.
Factual error: Mulder refers to a Royal Navy vessel that sailed from Leeds. No large ship can sail from there - it is at least 50 miles from the coast.
Graduation - S5-E24
Factual error: In the episode Class Pre-Union, they were the class of 2000. In the episode Graduation, they were the class of 1998.
Factual error: The originally-aired version spelled the word "Acquisition" without the "c" and it appeared in the credits as "Aquisition." This goof has been corrected in the DVD versions.
Return of the Green Ranger (2) - S2-E45
Factual error: Billy, Kim, Rocky, Aisha, and Adam return to Angel Grove in the 1700's...and there are British Redcoats there. On the West coast, in California. England never deployed troops to California, especially considering it was part of the empire of Spain at that time.
Factual error: Early in the show, 3 Marine officers are being questioned about the death of a 4th. All 3 are wearing the Marine insignia on their jacket lapels reversed. [The anchors should point IN, not out] That mistake is corrected for some characters later in the episode, however at least two of the officers are seen later without their jackets, and their shirts do not have military creases - 2 in the front, 3 in the back - standard for a Marine blouse.
Factual error: None of the Swedish wedding traditions Ingrid mention actually existed in the 19th century and the bread she's baked is not traditionally Swedish. When she later speaks in her mother tongue it's definitely not Swedish.
Factual error: "Treasure of the Ages": Haskell finds a jeweled cross that's supposedly from a shipwreck hundreds of years old. Only the relic he pulls from the sand is spotless: not a barnacle, rust spot or touch of encrustation on it. After centuries at the bottom of the ocean? Wouldn't happen. (00:02:00)
Shopaholic - S3-E6
Factual error: In the last scene, Fran has a soda cup from In-N-Out, which at the time, of the show, only had one restaurant out of the state of California, in the state of Nevada. Even today (2020), they don't have any stores east of Texas.
Factual error: Ben Franklin's "electricity kite" experiment and the Declaration of Independence happened 24 years apart, not at the same time.
Factual error: At about 8 minutes in, Grace's ex-husband is talking about flash flooding and water mixing with electricity. He's makes a comment about going up like Gary Gilmore. Gilmore was executed by firing squad and not in the electric chair.
Suggested correction: The entire series was set in an alternate history of sorts, so most, if not all, historical "inaccuracies" cannot be regarded as mistakes.
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