The 12-nation men’s competition begins at Deodoro Stadium today, with Britain drawn alongside pool opponents New Zealand, Kenya and Japan.
World Series title holders and top seeds Fiji go into battle as favourites, while the likes of Britain, New Zealand, South Africa and Australia should all be firmly in the medal mix.
And there is also huge expectation on a United States squad that includes Carlin Isles, world rugby’s fastest player, and Super Bowl winner Nate Ebner.
“The mood in the camp is brilliant,” Mitchell said. “There are always challenges when you are preparing a squad and when you are getting ready for the biggest event in sevens history.
“But from the very beginning when 27 players came together, we kind of forged a bond and bought into what we were trying to do.
“It has been an amazing journey to get this far, and everyone has played a huge part.
“We have got three tough group games, for sure, but there is a huge amount of talent in the squad and a lot of belief that if we do things right, then we should do very well in the tournament.”
Much of the British squad contains English players with vast World Series sevens experience, plus players like Scotland international Mark Bennett and highly-rated Welshman James Davies. Mitchell added: “The experience we have is important.
“We’ve got guys who have won tournaments in the World Series, and then you combine that with the sheer individual talent we’ve got. I think what we have seen in the last few years is how [sevens] standards are constantly increasing. We saw six different winners in the World Series this year, so that sets it up very nicely.
“We are really privileged to not only be here representing your country, but representing your sport in the Olympics. It’s the biggest stage there is.”
Fiji, coached by Englishman Ben Ryan, could land the country’s first Olympic medal in any sport as men’s rugby returns to the Games after a 92-year absence.
But the World Series season has shown the sport’s strength in depth, while New Zealand’s challenge includes the considerable presence of 2015 Rugby World Cup winner Sonny Bill Williams.
New Zealand coach Gordon Tietjens said: “We have seen in the recent World Series six different countries win the 10 tournaments. It is so exciting.
“Basically, it is anyone’s tournament.
“Unfortunately, the game of sevens is ruthless. One defining moment can decide a result.”
Britain face pool games today against Kenya and Japan, followed by New Zealand tomorrow, when the quarter-finals also take place. The top two teams in each pool, plus two best third-placed teams, will progress to the knockout stages.