There has been more than one Aunt Hortense in the Simpson and Bouvier families. In the Season 2 episode "Bart Gets Hit by a Car," Bart is on an escalator to Heaven and he sees an old lady on a cloud and says, "Aunt Hortense!"
When Bart shows Krusty's check at bank, Krusty is arrested four minutes later.
During Kent Brockman's report on Krusty being exposed for tax fraud, he repeatedly uses the term "tax avoision" despite his crew members insisting he use "tax evasion". "Tax avoision" is in fact a term, although Kent Brockman was indeed misusing the term, as tax avoision involves lowering personal payment of taxes in a way that's ambiguously legal (being a portmanteau of "tax avoidance", referring to lowering paid taxes in a legal manner, and "tax evasion", referring to lowering paid taxes in an illegal manner), in contrast to tax evasion, which deals with explicitly illegal lowering of one's personal taxes.
Taco Hut are parodies of both Pizza Hut and Taco Bell, both owned by Yum! Brands.
When the Sea Captain hangs up the phone when Bart and Lisa enter, he says "Call me back Ishmael." This is a reference to Moby Dick's famous opening line, "Call Me Ishmael."
The term "Krustyana" is a reference to "Disneyana", a collective term for vintage Disney merchandise.
The IRS Burger menu's food names are a reference to various tax-related terms:
Tax Burger is taxes.
IRS-wich is an obvious reference to the IRS (Internal Revenue Service).
Dependent-size sodas are a reference to "Dependents", or people who rely on another person for income.
FICA-ccino is a reference to the Federal Insurance Contributions Act tax, which is the law that mandates that any and all paychecks to various employees at various jobs have a significant percentage of their wages be taken away for tax purposes.
Although not menu names, the names for the trash and recycling repositories are called "Gross Refuse" and "Net Refuse", respectively, alluding to the gross and net index in economics.
Homer when comforting Bart about Krusty joining other celebrities in heaven, refers to Joseph Stalin, John Dillinger, and Ty Cobb as people Krusty is potentially meeting with (all three of whom were unpleasant people, the first being the dictator of the Soviet Union and a notorious mass murderer, the second being a notorious bank robber during the Great Depression, and the last one being an early baseball player who was extremely onerous).
When Krusty is talking to Bart about how low he has sunk, his beard is drawn over the top of his liquor bottle for a few frames.