Karev says that Webber was chief for 20 years. However, in the start of the season it was said that Webber was chief for 11 years.
When Karev and Robbins practice the flip, Karev's mnemonic was, "Yours over mine, everything's fine; mine over yours, babies in the morgue." However, when Webber stepped into Karev's place in the OR, the flip happened in the "mine over yours" fashion and yet the babies didn't end up in the morgue (the flip was successful).