Credit: Frank Micelotta/Fox/PictureGroup

American Idol is about the contestants, of course. But when you’re inside the Idoldome — especially amongst the throngs of fans who’ve come from the depths of the country for a little taste of Hollywood glamour, and especially when it’s a results night where one of their beloved potential Idols will bite the dust — it’s also about something else, something that somehow evokes something happier and more indulgent: the celebrities. And what a glittery, star-studded night at American Idol it was last night: Rihanna! Kelly Clarkson and Jason Aldean! Rob Reiner (yet again)! Chaka Kahn! Anita Baker! Mary Hart! And, of course, there were the regulars: Ryan Seacrest! Steven Tyler! Randy Jackson! Jennifer Lopez!

Inside the Idoldome, it was celebrity overload in the best way, and the crowds just loved it. And honestly, who wouldn’t get a little giddy over the chance to see what J.Lo is wearing; or a quick peek at Chaka’s hair; or the chance to be within reaching distance of Steven Tyler? Or, as this picture right here illustrates, the iconic meeting of Rihanna and J.Lo after the pop star performed her latest single “California King”? Fierce! Let’s take a glimpse at my time in the studio last night, an evening that was punctuated by celebrities, but as always and of course, defined by the singers who are vying to be the next American Idol and possibly future celebrities themselves. Here are the highlights from both ends of the spectrum:

• Lauren + Scotty = Cuteness: Could you even on any level with these two last night? First they performed Lady Antebellum’s “American Honey” superbly, and from that point on, I couldn’t consider them as anything but … a pair, a couple if you will. During Kelly Clarkson’s performance, they were the only two on the couches who had the gumption (or the respect? hello, she’s an Idol legend!) to stand and rock out a bit. Classy. Scotty, ever the country fan, was singing along the entire time. And: When Lauren got the news that she was safe, Scotty sweetly patted the spot on the couch next to him, with a grin on his face. I don’t know what’s going on here, but I’m just sayin’!

• Pia’s Here! When the warm-up comic told the crowds that bit of news, they went crazy. Last week’s cast-off was officially in the house! Actually, I saw her after the show, too, in the bowels of the studio, and she was wearing the most killer blue, tiny, slouchy mini-dress with classic Louboutins on her feet and a classic Louis Vuitton on her arm. One word: hot!

• Chaka Has the Best Fans: Jacob loves Chaka Kahn — is anyone surprised by that? You definitely didn’t see it on TV, but during one of the commercial breaks, Jacob made a beeline for the legendary Chaka to give her a hug, take a photo with her, and generally talk her ear off for most of the break (she didn’t seem to mind). And speaking of fans, Chaka was sporting the most delicious lady-fan of all time. She kept flapping it through most of the evening, and I couldn’t keep my eyes off it.

• Props to the Casey-Haley Collab, Too: I don’t want to give all the duo-love to just Lauren and Scotty. Where was this roaring Haley on performance night? The only distraction for the crowds was Randy, who wouldn’t stop ferociously pointing at the two of them (out of happiness) throughout their performance of Charles Mingus’ “Moanin’.”

• Mary Hart Represents: The outgoing Entertainment Tonight anchor was also in the audience. During a break, warm-up comic guy gave her an introduction to the crowd, and like you might expect, she, in that very Mary Hart kinda way, regally waved to everyone. But note: She wasn’t in one of the front rows. She was somewhere in the middle, which seemed sort of strange. But then afterward, it all made sense about why she was even there in the first place: I spied her doing a walk-and-talk interview with J.Lo through backstage about an hour after the show was over. (J.Lo seemed to be talking about what a nice life it is working on Idol!) Expect to see that on ET very soon.

• Comfy Kelly: She was in her element in the Idoldome, which makes sense since it was the place that initially made her a star. After her dazzling number, she headed straight for the judges’ table, natch, where she gave a big bear-hug to Randy and less-than-bear-hugs to J.Lo and Steven. She spent a lot of time talking to Randy, then the four snapped a photo before Kelly ran off the stage to cheers from the crowd, not too long before the show was about to come back from commercial break. Interestingly enough, she didn’t stop to dish with the contestants, even though she jetted right by their couch. But I’m guessing she spent a little quality time with them backstage. Or at least I hope she did! If anyone has advice for them, it’s probably her.

• The Bottom 3 Is Chilly: Maybe there was a blast of cold air on that side of the stage from the air-conditioning system, but did you all notice how frigid it was over in the Bottom 3 area? I know it can’t feel good to be over there, knowing that there’s a real possibility that you might go home. But when Stefano made his way over there, he and Haley didn’t even share a hug, or really a look at each other. And Paul didn’t give her one either when he sauntered over after he got the news. Weird? I thought so, but maybe I’m reading into it too much. Probably.

• Rihanna, the Runaway Star: After her sultry performance, Rihanna did the usual dog-and-pony show at the judges’ table, taking photos and making nice and all, but then she tried to run right backstage. Nu-uh, said stage manager Debbie, who grabbed her quick and — it seemed like she was almost doing a favor — introduced her directly to Lauren Alania. Then all the rest of the contestants huddled around, and Rihanna made nice with them for a couple of minutes. Not sure if she would have done that had Debbie not given her the hook.

• Idol Reactions: When Haley got the news she was safe? Casey went crazy, clapping like a nutbag. And when Stefano made his way back over to the couches? His big embrace came from James.

• Standing-O Central: Not sure if you pick up on this on TV, but literally, every single performance inside the studio seems to get a standing ovation these days. Like, not even kidding. I love a lot of what happens on the Idol stage (hello!), but does everything deserve a standing ovation? Um, no. But it’s something that always happens. It’s tiring being in there, all that up and down! Not sure if this is so much of a behind-the-scene observation or more of just a rant from Tanner.

• Wait, Who’s Safe? The interesting thing about being inside the Idoldome is what you can’t hear, actually. When Ryan made the announcement about who was going home — Stefano or Paul — there was literally five seconds where no one in the crowd even knew, partly because of sound issues (maybe?) but also partly because of the cryptic way in which Ryan likes to deliver the news. Anyway, it wasn’t until we saw Stefano heading back to the safe couches that we realized it was indeed the jovial Paul whose time was done. Hopefully you all at home could have figured it out a little bit sooner than we all who were on the inside did.

Do you have any further observations from the show? Questions? Sound off below, if you do!

Tanner on Twitter: @EWTanStransky

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