When Gai admonishes Kakashi for teaching Sasuke Chidori, Kakashi is standing behind Gai and a step above him and therefore two steps above Lee. Yet when Kakashi then talks to Lee in the next frame, he is beside Gai, only one step above Lee.
In the very beginning of the episode, when they pan past Choji, the mark on his cheek is missing.
Gaara: (Inside his shell) What is this...? It's so warm... What? Mother, what is it? (Blood drops on Gaara's hand, scene switches to outside the stadium) AAAAHHH!!! BLOOD! IT'S MY BLOOD!!!
Kankuro: Wha...? What's happening? (Sasuke tries to pull his Chidori out of Gaara's shell. Sasuke screams)
Temari: (Thinking) Impossible! Gaara in pain? (Sasuke pulls out his arm, and pulls out giant sand hand from Gaara's shell)
Baki, Temari, and Kankuro: The operation has begun!
Kankuro: Is that thing taking over again?
Temari: I don't know! This has never happened before! I think he's hurt.
Temari: Is it possible? Gaara's in pain?
Shikamaru: (Thinking) Hmph, look at him. A minute ago he thought Sasuke wasn't strong enough, now he thinks he's too strong and he's jealous.
Gai: Chidori! Also known as the Lightning Blade.
Sakura: Why is that?
Gai: It got that name because Kakashi once used it to cut a lightning bolt in half before it could touch the ground.
Sakura: (Thinking) Wow, cutting lightning in half!
Ino: (Thinking) Yeah right, these old guys and their war stories.
Choji: (Thinking) Whoa!
Kakashi: If you've wondered why I've insisted on training Sasuke myself, it's because he's a lot like me.
Kankuro: What's that lunatic think he's doing? How long is he going to stay in that thing?
Temari: I don't know, but he's not following the plan. He's no good to us like that.
Shino: (Overhears the conversation) Plan?
Kakashi: Keep your eye on Sasuke; he's about to surprise you.
Kakashi: You know Sasuke and I weren't just goofing around, there was a reason we were late getting here.
Naruto: This isn't the time to talk!
Kakashi: Exactly, so shut up and watch!
Gaara: What is this warm liquid? Mother, what happened? It's blood! MY BLOOD!!!
Gai: (After describing Chidori, he looks back at Kakashi) But, you've taught him a reckless move.
Kakashi: (Gives Gai a very annoyed look) I don't want to hear that from you. (Looks at Lee) Right, Lee? (Lee looks at Kakashi askance)
Poland Airdate: May 14, 2008
Jetix UK Airdate: June 11, 2007
YTV Airdate: February 9, 2007
Sasuke uses Chidori with his left hand, while Kakashi uses it with his right.
Original Airdate: January 14, 2004
Original Episode Title: I Wasn't Late for Nothing! Ultimate Move - Chidori revealed!!
Romaji Episode Title: Date ni Okureta wake ja nai! Kyuukyoku Ougi - Chidori Tanjou!!
Kanji Episode Title: だてに遅れたわけじゃない！究極奥義・千鳥誕生!!
Chidori means "A Thousand Birds". It got the name because the noise is creates sounds like the chirping of a thousand birds.
In this episode Gaara gets hit by Sasuke's Chidori, causing to bleed by the hands of another for the first time.
Regarding Kakashi and Gai's exchange about Kakashi teaching the Chidori to Sasuke, Gai is a bit of a hypocrite, seeing as how he taught Lee to open his internal chakra gates, something that had disasterous consequences for Lee.
Chidori, also known as the Lightning Edge, is Kakashi's only original jutsu.