Redmond was said to have a rare blood disorder named "Lubbock's Distemper," named for the Swedish scientist who isolated the disease about 25 years prior to the era of the episode. Lubbock's Distemper is, in fact, a non-existent condition.
When Artie is locked in the steam room, Artie acts as if the doorknob is very hot. Based on where the steam vents are (on the other side of the room), if the knob had become as hot as it appeared to be, Artie would probably already have been burned to death.
During the bedroom fight, Jim throws one thug into a chest at the foot of the bed, breaking the chest and knocking the thug out. The thug disappears for the rest of the fight, although the chest remains damaged.
The thug with the light tan pants and black vest is kicked and falls unconscious into the broken chest, lid open, falling closed (at 35:33); after another thug is knocked across the bed and falls over the broken chest, lid now closed (at 35:47), Jim moves the chest (at 35:49) and the thug's boot and pant leg are clearly visible within the broken chest (for a full 2 seconds). He quite CLEARLY has NOT disappeared. He's in the chest, visible the entire scene.
The thug with the light tan pants and black vest is kicked and falls unconscious into the broken chest, lid open, falling closed (at 35:33); after another thug is knocked across the bed and falls over the broken chest, lid now closed (at 35:47), Jim moves the chest (at 35:49) and the thug's boot and pant leg are clearly visible within the broken chest (for a full 2 seconds). He quite CLEARLY has NOT disappeared. He's in the chest, visible the entire scene.
During the stunt where Jim rescues Lavinia in the runaway carriage, it is clear that stunt people are standing in for both actors, being noticeably larger and heavier.
When practicing his ventriloquism, Artie was not really speaking for the dummy. Most of the time, his mouth is completely closed - when speaking for their dummies, ventriloquists must still have their lips open in order for the words to come out clearly enough for listeners to understand.
Jim lights three gas lamps on a wall. As he lights the first two, the room remains dim. As he goes to light the third, just before he lights it the room suddenly brightens, and then the third lamp lights, clearly demonstrating that the source of the light is the set's.
Jim triggers a booby trap which was supposed to have impaled him on his bed. The bad guys come into his room to retrieve his body. Jim jumps off from on top of the canopy and onto the bad guys, whom he quite naturally beats up. BUT canopies are NOT designed to hold the weight of a man, at least not those of the 19th Century. Rather, they are intended to hold wood furnishing which was designed to hold bed curtains or mosquito netting. Had anyone been so foolish as to try to get on top of a canopy, it most certainly would have collapsed under his weight.
Lavinia describes her brother as a "bio-chemist". The term "bio-chemist" wasn't coined until 1894, almost 20 years after the series is set.
In "The Night of the Turncoat" (S3.E13), while undercover, Artie had his right bicep prominently tattooed (visible from 12:19). However, during a massage at the Sedgewick Spa, both of his biceps are visible... and free of ink (and of any scarring that contemporaneous methods of tattoo removal would have caused).