In the episode "Spongebob Meets The Strangler", the Tattle Tale Strangler is based on a killer from the movie "Cry Baby Killer".
Whenever there is an accident involving the general population you can ALWAYS hear amongst the groans a man saying, "My leg...".Some examples are 1.In the episode "Hall Monitor" when spongebob directs all the cars in the wrong direction, you can see a bunch of wrecked cars, and then you hear the recording "My leg..." 2.And in "Boating School" when Spongebob crashes into the lighthouse you can hear a man moan "My leg..." 3.On "The Chaperone" episode, when all the kids at the prom get hurt during "The Sponge" song you can hear "My leg..." 4.This is the one in "Culture Shock" where Sqidward puts on a talent show.When Pearl puts on her performance, and jumps up and down, people start crashing through the air.At this part the "My leg..." sound is heard 5.On "Sleepy Time, when Spongebob is in Plankton's dream, Plankton says "Peek-a-boo I see you, Zap!!!", and you hear "My leg..." 6.In the episode "Aarrgh!", a fish walks in the Krusty Krab and says "Whip up those patties Crabs." and something else, and Mr.Krabs throws him out and he says "My leg..." 7.In "Walking Small", when Spongebob gets out his towel, he fans all the sound out of it.All the fish leave instantly.You can hear the recording "My leg..." 8.On "Karate Choppers", when Spongebob knocks a guy out thinking he's Sandy he says "My leg..." 9.And in "Something Smells" when Spongebob makes the marching band fall over and fly everywhere you can, once agin hear "My leg...".
In "Missing Identity," the waitress says "Well, you managed to kill 11 minutes." This is an inside joke because the average length of a Spongebob episode is 11 minutes.
In the episode "Karate" when Sandy is about to pour the hot sause over Spongebob's tongue, the face on the sause that laughs and taunts Spongebob is Tom Kenny, the voice of Spongebob.
In "Where's Gary?" when Spongebob takes the Dirty Bubble Challenge, look closely at the paddleball box; it has the Nickelodeon logo on it.
The guy taking a shower in "Neptune's Spatula" and "Suds" is Tom Kenny, the voice of SpongeBob.
The show Spongebob Squarepants was originally made for adults.