Three goals in an incredible 10-minute spell saw the Latics complete a stunning fightback over Arsenal at the DW Stadium on Sunday after Arsene Wenger's men took a first half 2-0 lead.
The win moved Wigan up to 15th and seven points above the relegation zone but McCarthy, who is fast finding his feet after signing from Hamilton last summer, is taking nothing for granted ahead of Saturday's trip to relegation rivals West Ham.
Committed: James McCarthy slides in on Arsenal striker Nicklas Bendtner
His side then entertain strugglers Hull City before travelling to Chelsea on the last day of the season.
Glasgow-born McCarthy, who somewhat controversially decided to represent the Republic and made his debut in the friendly against Brazil two months ago, said: 'It's a massive result considering we're fighting againstrelegation and now we've got another big game coming up this weekendagainst West Ham.
'Hopefully we can go down there and take all threepoints again. The gaffer's making sure everyone keeps their feet on the ground and he'll be having us work as hard as ever for the next game.
'This was a magnificent result but we've still got plenty of work still to do, and three huge games to go.'
Praise: McCarthy congratulates Ben Watson on his opener for Wigan at the DW
McCarthy says Wigan never gave up hope against Arsenal and hailed the contribution of team-mate Ben Watson, who scored the opener, followed by goals from Titus Bramble and Charles N'Zogbia in the 3-2 win.
'I thought we had to just keep working hard and keep moving the ball round as well as we were doing in the first-half and the majority of the second-half,' said McCarthy.
'It just goes to show that football is a funny game and anything can happen. We worked really hard after the break and although sometimes results haven't gone for us on Sunday they certainly did.
'They're (Arsenal) a top quality side and we knew how hard it was always going to be.
'But Ben (Watson) came in and I thought he was magnificent. His strike was great, deliveries all afternoon were accurate and getting on the ball he did very well.'
Wigan 3 Arsenal 2: Charles N'Zogbia scores late stunner to end Gunners title dreams Arsene Wenger blasts his bunch of bottlers as beaten Arsenal throw away title hopes at WiganWIGAN FC