Visible crew/equipment: After the ambulance arrives at the lion pit, just as the attendants reach the fence where John and Roy are standing, and the stokes is loaded onto the stretcher, we can see the two white tape marks on the ground, where the zoo employee is standing.
Visible crew/equipment: When we hear Station 51 being dispatched to the structure fire at Kiddytime Toy Factory, just as Roy rushes to the squad's door to open it, we can see the reflection of the camera dolly through the squad's windshield as it moves.
Other mistake: During the surgery on Brackett's father, after the closeup of the anesthesiologist there is a closeup of the Bird's Mark 4 unit, then a closeup of the bellows housing showing inflation and deflation, but on the bellows unit it reads "Animal Anesthesia Ventilator" made by Bird.
Continuity mistake: When the cardiac patient is finally brought to the ER, and goes into full arrest number four, he's wheeled into treatment 1 which does not have a window on its door, but in the next shot from inside the room the door has a window, and when they're defibbing him, we can see the nurses' station outside the door, which means he's now in treatment 3, not 1.
Other mistake: When Station 51 is dispatched to 'man trapped in vehicle', we can see the real Station 127's vehicle is still parked inside the apparatus bay, near the rear bay door.
Daisy's Pick Blind Date - S4-E7
Other mistake: When dispatched to the fire in the theater, the companies called are Station 51, Engine 85, and Station 36, but at the scene of the fire we see Engine 9 roll up and also see firemen with 19 on their helmets. These are shots from previous episodes including 3x7, "Promotion", when Roy and John rescue the security guard at the structure fire.
Other mistake: After Station 51 is dispatched to the 'vehicle accident with injuries', in the exterior shot as the squad and engine roll out, we can see the real Station 127's vehicle is still parked inside the apparatus bay, near the rear bay door.
Audio problem: After the sniper throws down the rifle, we see Captain Stanley start talking to Chet and Marco, though at first we don't hear anything, we then hear, "Put on your air masks, " but that is not Captain Stanley's voice we hear. Oddly enough, to me it sounds like John's voice. Have a listen.
Other mistake: When Station 51 is at the scene with the electrocuted man, he's dangling from a rope below the second stem of the letter H, in the large sign which reads "HOTEL", above the striped awning. In the shots from above the sign, looking directly down as they set up the ladder, we can see the letter H and the awning, but the dangling man is simply not there in the shots from this perspective, even though we should be able to see him.
Revealing mistake: During the fire at the apartment complex, there are strips of black material nailed to the tops of windows where the FX fire shoots out from below, and the doorway Roy passes when he's pulling on the hose has a fake ceiling and wall nailed directly into the door jamb, to control the strip of FX fire at the side.
Revealing mistake: At the apartment complex fire, just as Chet climbs the ladder and Marco holds the top of the ladder on the second floor balcony, we see the plumes of FX smoke spurting from the side inside the doorway behind them, and even see something quickly fanning the smoke.
Other mistake: At 6:50 AM, just before the dispatcher transmits the testing tones to Station 51 which wakes everyone up, we're shown the exterior shot of the station and the two flags are already flying. Guys of C shift (as Chet states) haven't arrived yet that morning, so they didn't raise the flags, and we know it's Mike who always raises the flags on A shift, but he only just woke up when the dispatcher sent the tones.
Other mistake: When Station 51 is dispatched to the structure fire, the address is given as 1127 West Winston, but when they're on the scene, the fire flashes through the front door causing Marco and Chet to fall back, and the house number on the stairs is 1026.
Daisy's Pick Blind Date - S4-E7
Other mistake: When Johnny and Roy are in the ice house, there's a closeup of Johnny's arms as he's hosing down the ice and removing it from the hypothermic victim's arm, but it's obvious that the dark hairy arms belong to the stunt double, not to Johnny.
It's How You Play the Game - S4-E19
Audio problem: At the scene of the vehicle accident, Johnny asks the driver, "Where does it hurt?" but when he continues to ask, "Right here?" we can see he's not actually moving his mouth, just before he's punched in the nose by the driver.
Camera Bug - S4-E10
Other mistake: At the end of the episode, when Johnny's telling the other guys that his photograph was bought, the box of cereal and carton of milk that are on the table have tape affixed to them, to deliberately cover their brand names.
Other mistake: When Squad 51 is dispatched to the liquor store shooting, en route they are almost hit by a driver who passed a stop sign at the intersection. This is the same footage from season 2, episode 13 "Drivers", when the squad is almost hit by a car while responding to a football injury.
Continuity mistake: After the Bengal tiger jumps on Les, the feline walks up the aisle that is directly in front of the self-serve ice cream freezer, and knocks over the pyramid of Hi-C cans that block the aisle, but a few shots later the tiger walks up that same aisle (note the ice cream freezer), and the mess of Hi-C cans have vanished.
Continuity mistake: After Johnny sees the Bengal tiger in the market, he backs away, and when Johnny is about to walk through the curtain, in the shot from the back room we see the tall shelving display of chip bags on the other side. However, in the next shot from the store that display of bags is gone, there's only a display of loaves of bread in front of the fruits and vegetables.
Deliberate mistake: At the market, after the tiger knocks over the pyramid of Hi-C cans, which were set up blocking the aisle just for that purpose, the officer tells Les, "Down that aisle," and the next shot of the aisle is a flipped shot - note the backwards words on the upside-down boxes. Two shots later that same aisle is shown properly, not flipped.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy