The Cod Army took the lead after just two minutes when Alan Goodall nodded home from close range.
But, after Town's Gareth Evans saw a penalty saved by Blues goalkeeper Paul Smith, the home side hit back with Corr coming off the bench to secure a share of the spoils for the Shrimpers with a well taken header in the 85th minute.
That was Southend's first shot of the game on target and, up until then, they had seemed destined for defeat after a bright start from Fleetwood.
They went ahead after just two minutes when Junior Brown's right-wing corner picked out Goodall at the near post and he bravely headed home from six yards.
Evans then had a 37th-minute penalty saved by Smith after Ryan Cresswell was adjudged to have handled the ball.
And the miss proved costly when substitute Corr headed home a left-wing cross from Britt Assombalonga to ensure the game ended level.