“It was a bit of a sticky start – they made a challenging start with two bowlers putting it in up front who got their rewards,” said captain Ben Trevor-Jones.
“But true to how we've gone about it this year, the middle order found a way to get us back on top and proceeded to take the game away from them really.”
Opener Brent Williams also added a useful 36.
Things had not looked as rosy at 62-4 before Mitchell and Ratcliffe made a game-defining 172 for the fifth wicket.
Yash Samra claimed 3-57 for Notts & Arnold.
Given a revised target of 273 from their 50 overs, Notts & Arnold collapsed to 156 all out in 35 overs.
Opener Johan Cronje hit 76 not out, but only Dilhan Cooray (43) stayed around to back him as no other player reached double figures.
Ben Bhabra took 4-19 off his five overs and Dillon Singh 3-38 off nine.
“Curtis is in some really good form at the moment and he scores so quickly. If he gets more than 25 overs at the crease he always put us in a strong position,” said Trevor-Jones.
“That was the case again on Saturday and Harry played a superb supporting knock with him.
“We lost a few overs to rain a couple of times, which probably cost Harry his 100, and I don't understand how Duckworth-Lewis took runs off us rather than giving us runs. That was really strange.
“To their credit they batted really well up top and put us under a lot of pressure early.
“But we took a couple of key wickets and once they were five or six down we were back on top.
“Then Ben Bhabra came back on and took four wickets in six balls which was incredible – all bowled and literally six yorkers in a row and took four wickets.”
On Saturday Papplewick play at home to Attenborough, who sit just a place behind them in fifth, and Trevor-Jones said: “Attenborough are another dangerous side with a couple of very good players in there.
“It is a huge opportunity for us to get another eight points, but we will have to play well.”