Corrected entry: In the scene where Gru is reading the bedtime story book about the unicorn that he wrote for the girls, there is a mistake with the hole in the book. He places his nose through the entire closed book which proves the hole should extend through all pages of the book but when he opens the book, there are no holes in the rest of the pages except the cover page.
Corrected entry: When Vector is bragging to himself in his bathroom after stealing the shrink ray, he fires it at the sink. The sink shrinks, but there should be water spraying out of the pipes. There is none. Same thing with the toilet.
Correction: The metal bends to accommodate the change between affected and non-affected parts of the pipe system without breaking. The same physics are demonstrated when Gru's ship is hit by the shrink ray. The ship shrinks in sections without breaking apart. Neither the toilet nor the sink should have broken pipes.
Corrected entry: If the effects of the shrink ray wear off depending on the size of whatever is shrunk then the moon should have returned to its normal size within seconds of being shrunk.
Correction: This entry is merely an assumption. It is made clear that the larger an object that the shrink ray is used on, the quicker the effects of the wear off, but that's it. There is nothing in the movie that states specifically how long it would take for the effects of the shrink ray on the moon to wear off, so this can't really be considered a plot hole.
Corrected entry: Gru pulls right up to Vector's place so the girls can deliver the cookies, in full view of Vector's cameras. How does Vector not notice Gru right outside his gate?
Correction: Although Vector has security cameras, Vector is never shown watching the cameras in this scene. When he is first shown in this scene, he is waiting at the door for Margo, Edith and Agnes to deliver the cookies, then after paying for cookies, goes back to his living room and watches TV. Even if the cameras taped Gru parking besides the house, there is no point in the scene that shows Vector watching the security footage, so he would not have discovered he was there.
Corrected entry: When Gru is looking at the statues in the Bank of Evil, the men holding the pillars are visible. In the next shot, when Gru is at the front, the last two pillars have no statues of men.
Correction: That is the joke. The statues depict a man struggling to hold up the pillars until they crush him. Which is why you see no statues on the last pillars.
Corrected entry: When Gru is waiting at the girls' dance class, the calendar on the wall behind him has only six days per week - Sunday is missing. (00:43:10)
Corrected entry: When the scientists are testing the shrink ray the elephant should have been shrunk to the size of a germ. Actually everything should have been shrunk to that size, except the moon which was bigger than the earth.
Correction: The hole for the unicorn horn (Gru's nose) is only on the cover of the book. Gru opens the book to put his nose through the hole.