This episode starts out at the Krusty Krab where SpongeBob is getting ready for closing time. He asks Mr. Krabs if he can buy a Krabby Patty for Gary because tomorrow is "Bring Your Pet To Work Day." So Mr. Krabs lets him. However, when SpongeBob checks the freezer, (along with all others) there are no more Krabby Patties left. He starts complaining to Mr. Krabs about this, so Mr. Krabs just decides they should make a fresh batch of Krabby Patties. Plankton is spying on SpongeBob and Mr. Krabs at this moment and he has an evil plan. Later that night, SpongeBob arrives at his home with some french fries for Gary. He then tells Gary that he needs a bath, which makes Gary run away. SpongeBob looks for him all over the house, and then he decides to give Gary his bath in the morning.
The next morning, there is a knock on the door and Gary answers it. It's Plankton in a salesman disguise. He claims that he's giving Gary a vacation to a Snail Resort for one night and tells Gary to wear a fake shell while he is there, while also lying about cleaning his real shell. Gary puts on the fake shell and leaves. Then Plankton gets into Gary's real shell, SpongeBob then gives Plankton (in the Gary disguise) his bath and while he's doing that, he discovers that "Gary" is green and talking, and he thinks that he is sick, so he takes Plankton to the hospital, where the doctor gives him bad news. They try every test imaginable; but nothing is found wrong with him (the doctors never saw anything like this) Plankton asks SpongeBob for one Krabby Patty before he dies, so SpongeBob starts taking him to the Krusty Krab. However, on the way there, Gary rides by on the bus and sees SpongeBob carrying Plankton disguised as himself. Gary gets mad, stops the bus, and gets out.
At that moment, SpongeBob puts Plankton in the kitchen and goes to make him a Krabby Patty. However, while he's waiting, the real Gary comes in and beats up Plankton, and Mr. Krabs sees him doing this and sees Plankton run out of the kitchen. So he gives Gary a job as a bouncer, with Gary letting people into the Krusty Krab one at a time, then Plankton comes, disguised again, this time as a small boy. However, Gary isn't fooled by the disguise and growls, causing Plankton to panic and run away. SpongeBob then says to Mr. Krabs how Gary is doing a great job as a bouncer. Then SpongeBob says "Really earning his pay," leaving Mr. Krabs shocked.
The title card is similar to the one of "SpongeGuard on Duty," but with a different kind of the life preserver and different background. The music is also different.
Towards the end, SpongeBob takes Plankton (dressed up as Gary) to the Krusty Krab to get him a Krabby Patty and SpongeBob calls himself, "Daddy." This is the first time SpongeBob called himself Daddy to Gary (or who he thought was Gary).
The pet hospital SpongeBob took Gary to is actually a hospital where fish go.
SpongeBob has talked to Gary before, but in snail language.
When Plankton and Karen do the "What?" exchange at the beginning of the episode, it may have been a reference to the stage act "Who's on first?"
Bring Your Pet to Work Day is a parody to Bring Your Kid to Work Day.
When Plankton and Karen were looking in the telescope, they saw Mr. Krabs and SpongeBob talking even though Mr. Krabs' office door was closed. It would be impossible for Plankton and Karen to spy on them directly across the street unless Karen had X-ray vision, being a computer, but that wouldn't explain how Plankton could see them.
Although Plankton never told him where Club Shell is, Gary somehow managed to get there.
When Gary blows at Plankton to get him out of the kitchen, he blows with 2 mouths (or possibly his nose).
Plankton's size becomes inconsistent when he's in Gary's shell; for example, when SpongeBob carries him down the stairs, he's larger than SpongeBob's hand. He's usually as tall as SpongeBob's finger.
When SpongeBob calls Gary a second time while Plankton was talking to him, only one eye moves.
When Gary growls at Plankton in the Gary costume, he has two mouths.