The show began with Ant and Dec reflecting back over the years and viewers couldn’t believe just how much had changed.
In homage to the ITV show’s landmark episode, the original titles on the show were played in place of the current one.
Viewers got a blast from the past when they saw the fresh-faced duo back in 2002, and they were stunned at just how far they’ve come in 16 years.
“Wow! Can’t believe how young @antanddec looked on their first show!! Now I feel b****y ancient! #cheerslads #SaturdayNightTakeaway,” one fan exclaimed.
While another questioned: “Love that they brought back the original opening titles for the 100th show of @itvtakeaway! How young do @antanddec look?! #SaturdayNightTakeaway.”
“Omg how young do @antanddec look in the original titles #legends #SaturdayNightTakeaway,” a third added.
“Omg Ant and Dec looked young I always think they never age but seeing that flash back shows they do just very well!! #SaturdayNightTakeaway,” said a viewer.
Another chimed in: “Oh my god how young do @antanddec look in 2002 when #SaturdayNightTakeaway started feel sooooooo old!!!!!!!!!”
The pair were just 26 when the show began in 2002 and have since enjoyed 15 series of the entertainment programme.
The special instalment wasn’t without drama however, as there were a few hiccups.
Scarlett Moffatt was accused by viewers of “fixing” a competition for a pair of fans to win a holiday.
During a part of the task where the two contestants had to find tickets in a slime-filled pool, Scarlett could be seen trying to covertly hand one of them an already used ticket, pretending that it was the last remaining boarding pass they needed to win.
Viewers noticed what she was up to and took to Twitter to comment.
One viewer tweeted: “Well that was a fix Scarlett clearly gave it him #SaturdayNightTakeaway.”
“Scarlett cheated lol that was the pass the woman brought into the pool #SaturdayNightTakeaway,” posted another.
Ant and Dec’s Saturday Night Takeaway continues Saturday at 7pm on ITV.