The star-studded finale of Season 18 of 'American Idol' included performances from Rascal Flatts, Cynthia Erivo and Lauren Daigle, in addition to appearances from some familiar faces. Ex-contestant Doug Kiker was given the best gift of the night with a surprise call from judge Luke Bryan informing him that he would get to perform 'Bless the Broken Road' with none other than Rascall Flatts themselves.

Kiker, a garbageman who won America's heart with his audition, was eliminated back in Hollywood. He kicked off the performance and introduced Rascall Flatts, who sounded as amazing as they always have. "Glad to see him back," tweeted one fan, another stated, "Doug is my absolute favorite!!!" and one fan shared, "Brought me to tears yall."

One fan quipped, "Meanwhile, the trashman is better than Francisco, Arthur, and Johnny." Fans were also ecstatic to see the Rascal Flatts perform. One fan said, "@rascalflatts will always be one of my favorites," while another shared, "Yes, thank you Gary. Missed that voice. @rascalflatts."

Following this emotional performance was another equally moving one featuring Lauren Daigle and Top 5 contestant Just Sam to perform Daigle's 3-time platinum hit 'You Say'. Sam has come a long way, going from the projects and singing on the subway to sharing a virtual stage with a Grammy-winning singer.

"'You Say' by @Lauren_Daigle has always been one of my favorite songs, and watching her and @CoJustsam sing it on #AmericanIdol just gave me chills galore. Amazing," tweeted one fan, while another shared, "The Just Sam and @Lauren_Daigle duet of #YouSay was a tear jerker. @AmericanIdol has tons of heart this season, when you strip away the flash of the stage show."

Not all were happy with the performance, however. One viewer asked, "Why is just sam the only one singing with a celeb? How is that fair?"

Closing out the guest performances was Emmy, Tony and Grammy-award winner Cynthia Erivo with a stunning tribute to the queen of soul herself, Aretha Franklin. Erivo was joined by this season's Top 11 for a medley of some of Franklin's top hits. "Nice tribute to the Queen of Soul!" tweeted one fan, and another said, "Who doesn't love celebrating Aretha Franklin's music? Cynthia Erivo and the Top 11 certainly know how to do it."

While most seemed to enjoy Erivo's tribute, some weren't quite so impressed. One fan stated, "@CynthiaEriVo is killing it on American Idol, I had no idea she could blow like that!" to which another viewer responded, "The contestants sounded better than her!" Another fan shot back, stating, "She sounds amazing to me," while one fan shared, "Ms. @CynthiaEriVo is pure MAGIC."

Some thought that Erivo was trying too hard, tweeting, "That was so forced! She confirmed tonight that she cannot sing Aretha songs!" as well as, "Idol finale video was weird...." along with a gif that read, "It feels fake."