1.In Gilmore Girls, a character introduces himself as "Mick" in the second episode. Four episodes later, the same character goes by "Kirk" and continues to go by "Kirk" for the entire series.
2.In The Office pilot, Michael says he's been with Dunder Mifflin for 12 years. Yet in Season 5, four years later, Michael claims to be celebrating his 15th year with the company.
3.Also in The Office, Pam's mom is introduced in Season 2, but when she reappears at Jim and Pam's wedding in Season 6, she's a completely different person.
4.And while we're still talking about The Office, Pam says she used to lie to get out of playing volleyball in high school, but it's later revealed she played the sport competitively through college.
5.In Sex and the City, characters used to break the fourth wall, speaking directly to the camera, but the series dropped those mockumentary-type interviews by the end of Season 2.
6.In That '70s Show, Donna has a younger sister named Tina who appears in one episode of Season 1 but is never mentioned again.
7.In Friends, Rachel and Chandler were introduced to each other three separate times — once in the present day and twice in flashbacks — as if they had never met.
8.Also in Friends, the ages of the characters are super inconsistent throughout the series.
Ross says he's 29 in Season 3, but in Season 5 he's somehow not yet 30.
Meanwhile, Monica claims to be 26 in Season 1 but turns 30 in Season 7 — meaning she's only aged four years over the course of seven seasons.
And Joey, who says he's 25 in the first season, making him the youngest of the group, somehow turns 30 before Rachel.
9.In SpongeBob SquarePants, there is a Season 2 episode where SpongeBob trips, causing multiple Krabby Patties to land in Squidward's mouth. However, in Season 3, Squidward claims to have never tried a Krabby Patty.
10.In Gossip Girl, Dan sends tips to Gossip Girl and is consistently shocked by new posts, even though it is later revealed that he was Gossip Girl the whole time.
11.In Full House, Jesse's last name was originally "Cochran" but was changed to "Katsopolis" in Season 2.
12.In The Nanny, the Sheffield residence has different decor and a different layout after the first episode.
13.In The Big Bang Theory, Howard has no idea the elevator is broken in Season 1. However, in a Season 3 flashback, it's revealed that Sheldon, Leonard, Howard, and Raj were the reason the elevator broke in the first place.
14.In The X-Files, Mulder is seen wearing a wedding ring in a Season 5 flashback episode, but there is no mention in the show of him ever being married.
15.In New Girl, Jess tells Winston she's claustrophobic, even demonstrating her fear by locking herself in a closet and screaming for help. However, just one episode later, Jess hides in a closet with multiple characters and has no panic attack.
16.In Hannah Montana, people know Robby Ray is Miley Stewart's dad, and he also claims to be Hannah Montana's dad. Yet somehow, no one is able to piece together that Miley and Hannah are the same person.
17.In Cheers, Frasier claims his father was a scientist before he died. However, in the spinoff Frasier, Martin Crane is very much alive and worked as a cop, not a scientist.
18.In TheGolden Girls, Blanche once said she had four children, but as the series progresses, it's revealed she has six: four sons and two daughters.
19.In Family Matters, Judy completely disappeared after Season 4, and the Winslow family never offered any explanation for the youngest daughter's absence.
20.And in Riverdale, Jason and Cheryl Blossom are supposed to be twins but are in different grades at school.