Revealing mistake: At the site of the hang gliding accident, just after the glider falls, in the long shot when Johnny and Chet pull the unconscious victim higher on the cliff, the victim is supposed to be unconscious, yet we see him use his right leg to push himself higher up to help John and Chet pull him up.
Visible crew/equipment: When Roy is in the ER due to the dizziness, two actors' T-marks are visible on the floor near the door, where moments later Dr. Bracket and Dr. Early stand before leaving. Additionally, Dr. Early's mark (during The Exam) becomes visible when Dixie shifts her position, just as Dr. Bracket asks, "Any pain here, Roy?"
Visible crew/equipment: When Mr. Grady (self-defense instructor) is in the ER, being examined by Dr. Brackett, there is a visible T-mark on the floor behind Gage.
Visible crew/equipment: After Station 51 is dispatched to the fire at a singles club, when Engine 51 pulls into the parking lot it and then turns around, the reflections of multiple array lighting can be seen on the engine's surface and Mike's window when he opens the door.
Other mistake: When the self defense instructor tries to use Mrs. Pestone to demonstrate the flip, he puts his arm around her and covers her mouth, then it cuts to a shot of Squad 51 rushing down a street. This particular shot is from 5x8, "The Lighter-Than-Air Man," when Roy drives past the school kids and crossing guard.
Other mistake: During the singles club fire, after Johnny and Roy check the men's room upstairs, there's a shot of firemen in full turnout gear with hoses, and this footage is from the first season's pilot episode, "The Wedsworth-Townsend Act."
Other mistake: During the actual cliff rescue of the hang gliding accident victims, Roy and John are wearing hiking-type shoes with ridges on the soles, not their uniform shoes.
Continuity mistake: When Morton and Early are examining the guy with stomach pain and cramps, Morton's stethoscope is around his neck with the earpiece at his left and the chestpiece to his right, but in the closeup it's the opposite way around, then it's back to the original way.
Continuity mistake: Just before Engine 51 and Squad 51 arrive at the scene of the hang gliding incident, there's a long shot of the victims lying injured on the side of the cliff, and when the camera zooms out we see Johnny and Roy with the informant of the accident standing at the top of the cliff, even though Squad 51 hasn't actually arrived at the scene yet. That same shot is shown a minute later after they all arrive, when Roy says that he'll get some equipment.
Continuity mistake: When Johnny and Roy rappel down the cliff with the downed hang gliders, both of their lifebelts are buckled going from their left to right sides, but in Johnny's first closeups when he's with the second victim, Johnny's lifebelt is on the opposite way, note that it's buckled going from his right to left. Then once the glider falls Johnny's belt is on the original way.
Continuity mistake: When Roy and Johnny begin rappelling down the cliff to the injured hang gliders, Roy's not wearing the safety pack in the closeup, but as they're rappelling in the wide shot the large safety pack is suddenly on Roy's back.
Character mistake: When Mr. Grady, the self defense instructor, and his wife are in the ER waiting room after Brackett taped up his fractured ribs, Mr. Grady makes a comment about being flipped, and instead of saying Mrs. Pestone he says the name incorrectly as Prestin, then a few moments later he says her name properly, just as he did earlier during the class.
Visible crew/equipment: At the site of the hang gliding accident, when Captain Stanley and Marco are pulling the stokes up the side of the cliff, the outlines of the lav mic transmitter and wire are visible on the back of Cap's shirt.
Visible crew/equipment: After Brackett examines the self-defense instructor, when Brackett speaks to Mrs. Grady in the hallway, the outline of the mic transmitter is visible at the front of Roy's shirt.
Visible crew/equipment: Near the end, when Johnny's walking from the locker room to the kitchen and checking his watch, the bulging outline of the mic transmitter is visible on the front of his shirt.
Visible crew/equipment: When Roy and John are treating the self-defense instructor, the outlines of the mic transmitter and wire are visible at the side of Roy's shirt.
Revealing mistake: When Station 51 is dispatched to the hang gliding accident with two men trapped on a cliff, as the squad and engine roll out of the bay, we can see the real 127's vehicle is still parked in the apparatus bay, near the rear door.
Visible crew/equipment: When the self-defense instructor is teaching the class, the outline of the mic transmitter is visible on the front of his shirt, particularly when he tells the ladies, "Here's a little bit of judo that you'll all be learning too."
Continuity mistake: When dispatched to singles club fire, Engine 51 pulls into the parking lot, and there's a shot of Mike hooking up the supply line to the hydrant, with Marco at the side of the engine, but it cuts back to Engine 51 in the lot again, with Mike behind the wheel and Marco sitting in the jump seat, and there is no supply line hooked up, then the engine drives further into the lot.
Continuity mistake: At the singles club fire, after Roy and Johnny go in to look for the missing man, we see Mike charging the lines, then there's a shot of two of 16's guys walking past the stairway with a hose, and notice that on the stairway we can see Johnny's and Roy's legs heading down the stairs. This same shot is shown again after Roy and Johnny check the men's room upstairs, and once again we see Roy and John coming down the stairs when 16's guys walk past them.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy