The pop princess fired off a series of live Tweets during the show's West Coast airing, sharing memories from the set and opinions of the show and its stars as the episode was soundtracked by her greatest hits.
Brit's first Tweet popped up on her account when cheerleader Brittany, played by Heather Morris, revealed that her real name was the same as the pop star's – pronunciation-wise.
"Awww Heather Morris is sooo cute! Brittany S Pearce," the "Lucky" singer Tweeted. "Ha! She was so fun to work with and was really sweet in person."
Britney's next observation occurred when "Glee" newest guest star made his first appearance on the small screen.
"John Stamos is still hot!" she wrote of the actor who is guest starring as Carl Howell, a dentist and new love interest to school counselor Emma (Jayma Mays' character).
"He looks the same as he did on Full House," she continued.
Chris Colfer's character also got some praise from the "Circus" singer.
"I like Kurt's bow tie. Bow ties are sexy," she wrote, later adding, "Kurt wears some pretty fabulous outfits."
Another comment from the international superstar praised the pint sized dancers who backed up "Glee's" own Brittany, who donned a "Toxic-esque" catsuit as she performed "I'm A Slave 4 U," while under a dentist's anesthesia.
The real Britney also praised McKinley High's Brittany (Heather) on her handling of the "Slave" snake.
"I know how hard it is to dance with that snake! Nice job," she wrote.
Later, Brit Brit had praise for Brittany's cheerleader best friend Santana, played by Naya Rivera.
"The Me Against The Music set looks just like the original. Santana does a great Madonna impression," Brit wrote.
Lea Michele, who plays Rachel Berry, performed "…Baby One More Time," and it took the pop princess back.
"Watching Baby brings back so many memories! Feels like yesterday…" she Tweeted.
Even Josh Sussman, who plays high school journalist Jacob Ben Israel, got some love.
"That's a serious afro ya'll!" Brit wrote of his hair.
Britney didn't actually get to film a scene with Jane Lynch, and when the scenes featuring Sue Sylvester came up, the pop star wrote, "Jane Lynch scares me."
The pop star was impressed with Kevin McHale's take on one of her early hits.
"I love this version of Stronger. Artie did a great job," she wrote.
Britney ended her "Glee" Twitter night, writing, "I loved it! Thank you guys SO much for making this happen!"
To read all of Britney's Tweets, click HERE.
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