I know of the famous adlib scene in I Love Lucy where Ricky is translating back and forth and Desi goofs up his line but they roll with it, but what are some other scenes that were either confirmed or definitely seem like they weren't in the script?

Another great one is from "The Phil Silvers Show" episode "The Court-Martial" where Bilko acts as a lawyer for a monkey who somehow enlisted in the Army. At one point, the phone rings, the monkey goes to pick it up, and Bilko says "He's calling for another lawyer!" A great moment from an incredibly funny episode.

I'm not 100% sure that this is one, but in one of the Hollywood episodes of I LOVE LUCY Ricky brings William Holden up to the Ricardos hotel suite. Lucy, Ricky and William Holden are all sipping coffee and Lucy is wearing a fake nose. She puts a cigarette in her mouth and Holden reaches over with a lighter to light it, but he accidentally lights her nose. So she just bends her head down and dunks it in her coffee.

on MORK & MINDY Robin Williams would often ad-lib some of his lines.

In the Bupkis/Nothing episode of the Dick van Dyke Show, Rob heard a song on the radio and called the radio station. DvD messed up and dialed the phone without looking in the phone book next to it. While it was "ringing", he then looked in the book and said, "r-i-i-i-g-h-t," like he actually knew the number all along and was just confirming it in the book.
that episode is named BUPKIS

I don't know if this counts but on THE DICK VAN DYKE SHOW Buddy originally wasn't going to make cracks about Mels baldness, but once during a rehearsal Richard Deacon flubbed a line and Morey Amsterdam said "Dick, I think I know what happened to your hair. It didn't fall out, it fell in and it's clouding your brain!" Carl Reiner thought it was funny so he decided to make Buddys cracks about Mels baldness a regular feature.

I've read that in the Seinfeld episode The Implants where Jerry and Elaine get obsessed with figuring out if Teri Hatcher's character's breasts are fake or not, Teri Hatcher ad libbed the line "They're real and they're spectacular!"

Ed.

The "There'll Be Some Changes Made" episode of Sanford & Son. The tag scene where Fred pulls the wig off Aunt Esther's head. :lol:

In the pilot episode of Frasier, Jane Leeves' character Daphne is being introduced. She's sitting on the couch talking to Frasier and Martin and she mentions being psychic. She figures out Martin was a policeman but was wrong when she thought Frasier was a florist.
Daphne then defends herself and says that her psychic powers come and go but work best during her time of the month. Frasier ribs her a bit telling her that was a bit more than was needed to know, then suddenly Daphne points to Eddie and says; "You're a dog, aren't you!?" then she laughs.
That part was actually ad libbed by Jane but they loved it so much it was left in. Classic scene and hilariously funny. :D