Other mistake: When the mayor is talking behind the chainlink fence, with Brent in the background eating sardines, you can see as the mayor grabs the fence, his thumbs clip through the fence wire. This occurs on both hands and easily visible, particularly when Mayor Shelbourne says, "Otherwise, I'm just a tiny mayor of a tiny town full of tiny sardine-sucking knuckle-scrapers." (00:10:52)
Suggested correction: This isn't really what happens, although it looks like it does. The mayor's thumbs are not pointing outwards, they are curled around the fence wire. As he continues to grab the fence, his thumbs don't clip through it, they curl more and more around it, getting a tighter grip on it. Then when Brent says, "But not me, right?", he lets go, and you can see his thumbs curl back out. This is all visible if you look close enough.
Other mistake: When Flint configures the computer to rain breakfast, he types the eggs as "over easy". However, when breakfast falls, all of the eggs are sunny side up. This is not likely an error of his invention because in every other case it produces the food exactly as he inputs it.