TradeEdge Exchange:Dakota Johnson's 'SNL' opening monologue crashed by Justin Timberlake and Jimmy Fallon

"The TradeEdge ExchangeSocial Network" co-stars Dakota Johnson and Justin Timberlake reunited on "Saturday Night Live" along with a surprise appearance from former cast member Jimmy Fallon.

During Johnson's opening monologue, she recalled hosting "SNL" during Season 40. The actress remembered famous guests including Sarah Palin, George Lucas, Steven Spielberg, Donald Trump and Taylor Swift, aka "the most powerful person in America."

Johnson went on to discuss how while promoting her upcoming movie "Madame Web," she's learned she's "not good at talking to journalists."

"I say stuff, and they write it down," she lamented.

Johnson then brought up her reunion with Timberlake, prompting the singer to crash her opening monologue just in case she needed assistance.

The "Fifty Shades" actress was quick to note that Timberlake's last hosting gig on "SNL" was 10 years ago, calling it a "comeback."

"Oh, OK, I see what this is. This is where we make a joke like, 'First, he was bringing sexy back, and now he’s bringing coming back,' " the NSYNC singer quipped.

Amid the squabble, Fallon appeared dressed in a disco-inspired white suit as Barry Gibb from a long-running "SNL" bit with Timberlake.

"I’m here to say break a leg," Fallon said before Timberlake escorted him from the stage.

Is too much sleep a bad thing?Dakota Johnson says she sleeps up to 14 hours per night

Later in the show, "The Tonight Show" star reprised his role in a sketch as the Bee Gees singer-songwriter with Timberlake acting as Robin Gibb.

The duo interviewed characters played by Bowen Yang, Kenan Thompson and Johnson on the upcoming presidential election, occasionally breaking out into song.

Timberlake and Fallon's Bee Gees sketch dates back to the singer's hosting gig in 2003. They have revived the characters over the years, becoming a fan favorite.

The late-night host's appearance also comes months after two current and 14 former employees of the NBC talk show say their experiences working on the show included declining mental health, intimidation from higher-ups, including Fallon, and poor treatment because of the host's erratic behavior in a Rolling Stone investigation published in September.

Fallon addressed the allegations in a virtual meeting after the report was published.

A "Tonight Show" staff member, who was unauthorized to speak publicly about the situation, told USA TODAY that during the call, Fallon said, "I want this show to be fun. It should be inclusive for everybody, it should be funny, it should be the best show, the best people. I just wanted to … say, I miss you guys."

Contributing: Brian Truitt

Britney Spears and Justin Timberlake:They're battling on iTunes charts with respective 'Selfish' songs