I just was watching a taped episode I had of DS where Sam wet his bed. Now to make Sam feel better, Arnold told Sam about something that was he was embarrassed about when he was little. He said that until he was 9 ( 1st Season ) He had to sleep with a doll. However he said the doll was called FoFo. Wasn't it Homer???

I noticed that too, I thought that was a bit stupid that the writers put that clearly without doing proper research.

Another mistake I just noticed is in episode 54- Football Father, when Dudley gets picked in the team the coach calls him "Ramsey" but that was before he was adopted. I episode 71- Room For one more Arnold says to Drummond "you know my friend Dudley Johnson".

He also called him Dudley Johnson in the Court episode. I got another mistake for you. Willis was 12 when the show started which means he was 18 in 1984 so how come he didn't go to college untill 1985. It was said that he was 14 in 1979 so how come people kept switching back and fourth.

In the first ever episode when Kimberly first sees Willis she says welcome big brother but a year later in 1979, the episode "The Landlord" Willis is said to be 13 and Kimberly 14!

I don't think they ever really decided on Willis's age, they just changed it around as they felt like it.