In another episode, Squidward's singing voice is shown to be terrible. But when he sings 'Beautiful Dreamer' over the credits of this episode, he's actually pretty good (much like his clarinet playing).
When Patchy the Pirate arrives at Nickelodeon Studios, the wind nearly blows his beard off.
Plankton is celebrating 50 years in business while Krabs is celebrating 117 years, which in itself makes no sense, but yet both businesses opened the same time.
The flashback to SpongeBob as a baby is set somewhere between late 1986 and early 1987. Squidward is shown as an adult at the register, and the way he looks in the present. His birth year is undisclosed, but if it was 1966 then in the flashback he would be twenty years old and have a full head of hair, and if it was 1977, then in the flashback he would be just nine. Furthermore 'Goodbye Krabby Patty' shows that Squidward didn't start working at the Krusty Krab until 1999.