When Marge remarks that a family of possums live in the fire extinguisher compartment of the monorail, her necklace and Maggie's pacifier are gray-brown instead of red.
There is no possible way the small stack of bills Smithers gives to Judge Snyder could be $3 million. Later the money is shown filling two large briefcases being carried around by Lyle Lanley. The largest bill ever produced by the U.S. government was $100,000 (in 1934), but these were issued as large certificates and not small bills. Upon close inspection, the bill on the top of the stack is for $5000 and there appear to be about 11 bills, so assuming all the bills are $5000, this would only be $55,000.
The Monorail Cafe employee's lips aren't moving when she says "Go away!" to Marge.