Revealing mistake: Whilst Bobby is reversing the truck before hitting the flagpole in Bill's yard we see the driveway in front of the truck. The very next shot shows Peggy from behind the truck instructing him how far to go to the flag pole and you can see they have used the same background as the shot before from the other angle. You can tell this as both shots are the same background as both angles despite from different viewpoints are exactly the same items and objects in both shots. Added to this there is a driveway in each shot, and Bill doesn't have 2 driveways in his backyard.
Continuity mistake: Bill picks up the case of Metalife products to put them in his car. After discovering he has a blister he picks up the box and the logo on the box is facing the left-hand side. The next shot it's changed to the front of the box. The change of shots was instant so there was no chance he could have turned the box around.
It's Not Easy Being Green - S5-E16
Continuity mistake: When Hank, Dale & Bill go to the quarry to get the car, they use a tow truck to try and pull it up. If you look at the tow truck you can see it is a red color. Later on when the protesters come and are sitting in a circle and singing the tow truck is now orange. It stays orange for the rest of the scene.
Continuity mistake: When Hank goes to buy an "L pipe" at the Mega Lo Mart, his truck is parked in the middle of the parking lot and nothing in between the middle of the cars. As Hank is about to leave in his truck there are concrete blocks ahead of his car (with a sidewalk next to them). Also if you look at the car behind Hank's truck before he is about to leave it is a white color. Whilst he is reversing it is now a dark blue color.
Three Coaches & a Bobby - S3-E12
Factual error: Before Hank knocks Coach Sauers out with the drink case, the coach starts up his car, but when Hank knocks him out the engine turns off as soon as Hank hits him. The engine wouldn't turn off because of being unconscious. (00:16:20)
Won't You Pimai Neighbor? - S4-E18
Deliberate mistake: Before Bobby takes the final spiritual test, you can see Connie is behind Bobby with her parents. When Bobby starts looking at the objects she has moved over to the right of Bobby nowhere near were her parents were before. This would have been deliberate for when he's taking the test he picks Connie in the mirror and this would have been impossible to do if she was right behind him.
The Wedding of Bobby Hill - S3-E14
Revealing mistake: During Rad's haircut from Luanne, there is a shot that shows the both of them in the mirror. You can see both their reflections and the room in the mirror but the objects on the counter in front of Rad have no reflection.
Continuity mistake: At the end when Laoma is crying and hugging Bill, the tears on her face are on her cheeks. As she asks, "Wait, Astronaut who?" the tears are now just found near her eyes. As Bill explains, she has her hands on his shoulders. She then turns and the tears are not even in her eyes now.
Escape from Party Island - S3-E17
Continuity mistake: As Hank is driving, whilst trying to get off the island, a large Alamo beer display can drops in front of the van. In the next exterior shot you can see it actually drops again but to the left of the van.
Continuity mistake: When Hank Hill decides to take his son, Bobby, to shoot a deer at a local recreational resort named La Grunta, Hank shows Bobby what is supposedly a La Grunta brochure, but the description at the bottom-right of the brochure states that the text therein is referring to the "Shropshire House Inn & Resort."
Character mistake: In Episode 1.11, Hank says "McDonnell Douglas L-1011" when it is really Lockheed L-1011. McDonnell Douglas produced the DC-10, which was similar.
When Cotton Comes Marching Home - S5-E5
Continuity mistake: Before Topsy (Cotton's friend) & Cotton tie up the restaurant manager there is a quick shot that shows the sign on the door for the men's room. It has the symbol on it for disability access. However in one of the previous shots when Cotton tries to leave the restaurant the sign is the same but there was no wheelchair accessible symbol.
Megalo Dale - S7-E10
Continuity mistake: Chuck Mangione is shown living in the Mega Lo Mart, having faked his death after the explosion. Yet, he was shown in "Death Of A Propane Salesman" at Buckley's funeral.
Square-Footed Monster - S13-E3
Other mistake: When Lucky drives off in the pickup with the tow chain, as the McMansion crumbles to the ground, Luanne runs away from the house, and part of her legs are missing. The animation is incomplete.
Other mistake: When Hank tells John Redcorn that his family is not Jewish, John is noticeably surprised. However, in the episode "Revenge of the Lutefisk" (3x21), John was at church with the Hills and Gribbles. He already knew that they are not Jewish.
Continuity mistake: The entire episode is about Hank being very attached to his current truck, and refusing to purchase a new one (until he has no choice). But in S4 E23 Hank tells Peggy "You know how much I want a new truck."
Death of a Propane Salesman (2) - S3-E1
Continuity mistake: When Peg is on the phone with Buck the wall telephone has a long cord, then she hangs up the receiver on the wall, but in the following shot both the receiver and its long cord are weirdly missing from the wall phone. (00:05:15)
Other mistake: The reflecting light on the water is on the wrong animation layer, appearing over anything else in the scene that comes into their position, despite being in the background. (00:20:40)
The Year of Washing Dangerously - S10-E9
Continuity mistake: Peggy is looking out the kitchen window into the Gribble household, which is wrong. Khan lives on the kitchen side of the Hill household. The Gribbles live on the garage side.
Nine Pretty Darn Angry Men - S3-E7
Continuity mistake: When Peggy's shoe sole comes off, it comes off the right shoe, but in the repair shop she hands her left shoe to the cobbler.
Answer: Jeffrey Boomhauer is a Texas Ranger as can be seen in the final episode at the end when he sets his wallet down, it flips open revealing a Texas Ranger badge.