Chapter Two: The Mall Rats - S3-E2
Continuity mistake: Steve throws his empty banana peel on the table in the back of the ice cream store, then is shown seconds later still holding the empty peel.
Chapter Five: The Flayed - S3-E5
Continuity mistake: When Hopper is taking Todd's car at the gas station he hands Todd a Slim Jim he was eating, then they pan away from them to show Joyce Byers and Hop talking. When the scene widens Hop has the Slim Jim back in his hand and hands it to Todd again. (00:24:25)
Chapter Five: The Flayed - S3-E5
Continuity mistake: While Hopper lies his way into stealing the car from Todd and claims that Alexei has murdered many children, Hopper pushes the driver seat back into its proper upright position. Then as Hopper introduces Detective Byers to Todd, the driver seat is once again leaning toward the steering wheel before being upright in the next shot. (00:24:30)
Chapter One: Suzie, Do You Copy? - S3-E1
Continuity mistake: When Billy crashes his car, it stops and breaks down. He moves to the bonnet and a clear hissing from a damaged is audible. Then all the mess happens and the episode ends with the usual cliffhanger. When the second episode starts, Billy's car battery is still up, even with the headlight turned on, and the car starts at once with no problem whatsoever.
Chapter Five: The Flayed - S3-E5
Continuity mistake: In the woods, when Alexei is running with Hopper chasing after him, the individual shots of each of them running are flipped. Note Alexei's shirt pocket and Hopper's bloody head wound. (00:22:30)
Chapter One: Suzie, Do You Copy? - S3-E1
Continuity mistake: In Bruce's hamburger the salad is on the bottom and the bacon is on the top, in the next shot the salad is on the top and the bacon has disappeared, replaced with ketchup. (00:23:05 - 00:27:10)
Chapter Seven: The Bite - S3-E7
Continuity mistake: At the very beginning the band the camera pans by is totally different from the one standing behind the mayor later on. For one there are no more clarinet players, a cymbal player suddenly appears right behind where the mayor stands and the drummers are 3 totally different boys, with the 3rd from the right missing his glasses suddenly and the second drummer being much shorter. (00:00:40 - 00:01:15)
Chapter Six: E Pluribus Unum - S3-E6
Continuity mistake: When the librarian picks up the phone he picks up the one in the middle, in the next shot we see he has the one to the left and when he hangs up it's the one in the center again.
Chapter Five: The Flayed - S3-E5
Continuity mistake: When Robin takes the chemical container off Erica, in the shot of Erica saying "It could be useful", Robin is holding the container upright. In the next shot, it is being held at a rotated angle, then upright in the following shot. Two shots after that, the container is suddenly rotated again, then back to upright when the shot cuts. (00:17:25)
Chapter Five: The Flayed - S3-E5
Continuity mistake: Eleven and Mike are sitting next to each other at the hospital. Eleven looks to her left in one shot and the camera changes angles. She's now looking straight ahead and immediately looks to the left again.
Chapter One: Suzie, Do You Copy? - S3-E1
Continuity mistake: Steve is talking to Robin about striking out. Two girls come in and Robin encourages him to talk to them. In the first angle his shirt is lower and you can see his chest hair. Cut to the other side as he flips around to talk to the girls, and his shirt has moved up. (00:24:15)
Answer: The body was fake, made by the scientists at Hawkins Lab in an attempt to cover up his disappearance and the existence of the Upside Down.