Three's Company (1977)

Continuity: After Jack brings the puppy over to the girls, the box he brought the puppy in was placed on the table behind their couch. At one point, it is knocked over, and you can see it falling down to the floor (past Janet). In the next shot, it's back on the table, and none of the characters were in a position to pick it up to place it back there.

Continuity: Larry gives Cindy and Janet gifts to thank them for letting him live with them, so Janet gives him a kiss. However, three seasons later in the episode "Friends and Lovers," Janet kisses Larry at her wedding to which Larry says "Janet, that's the first time you've ever kissed me."

Revealing: In the scene where Jack and Janet are sitting on the sofa with the doctor, Janet offers the doctor some nuts from a bowl. Then take a look at Janet's face. She begins to laugh so she lowers her head and the camera immediately shoots over to Jack who realizes the goof and adlibs something to give Janet time to get into character again.

In the episode where Janet asks Jack if she's a bad kisser, take a look at Janet when he kisses her. Jack unexpectedly slip Janet his tongue (which surprises the audience as well) and that throws Janet off and shocks her. Her surprised face is not acting, and was really surprised he did that. You'll also notice that when they part, she can't keep a straight face.