Blackburn eased past Colchester after a howler from goalkeeper Aidan Davison set them on their way.
Davison tried to kick Kevin Watson's backpass up field but failed to make clean contact and the ball scuffed off his foot and into his own net.
Jemal Johnson drilled the ball past Davison from 18 yards for Rovers second, while the U's keeper twice denied David Thompson before the break.
Dominic Matteo diverted Robbie Savage's free-kick home for Rovers' third.
Blackburn, playing in front of a crowd of just 10,634, started at a brisk pace and dominated throughout against their League One opponents.
Johnson broke down the left in the sixth minute but his teasing cross was cleared, while Morten Gamst Pedersen shot wide after the outstanding Brett Emerton laid the ball into his path 18 yards from goal.
Savage narrowly missed with a curling free-kick before Gavin Johnson had an opportunity to give Colchester a shock lead.
The 34-year-old struck a sweet half-volley from 14 yards but his strike was directed too close to Brad Friedel, who comfortably saved.
Colchester seemed to have resisted Rovers' early pressure when Davison's horrendous mistake put the Premiership side in front.
And shortly afterwards Rovers' pace down the flanks again exposed the U's backline.
Thompson's low pass from the left was laid off by Pedersen into Johnson's path and the American placed the ball beyond Davison for Rovers' second.
Davison twice saved from Thompson before the break as Rovers pushed for a third.
Rovers extended their lead shortly after the break when Matteo got the finest of touches to divert Savage's drilled low free-kick past Davison.
Emerton a 20-yard strike narrowly wide as Rovers continued to open up the Colchester defence and he was thwarted by Davison minutes later.
Johnson wasted a good chance to reduce the deficit midway through the second-half, miskicking from 10 yards after good approach work from Greg Halford.
And with full-time looming Freidel saved well with his legs to deny Guylain Ndumbu-Nsungu.
Blackburn boss Mark Hughes:
"I'm delighted for Jemal Johnson. He's a young player who has come through the academy and who we think has got a good future here.
"It was an opportunity to get him on the pitch and get him some game time and he did very well.
"His movement was good, he was involved in most of our attacking work and also pinched a goal with a good strike."
Colchester boss Phil Parkinson on Davison's mistake:
"It will no doubt be shown on Match of the Day, and probably on programmes in years to come.
"But he is an experienced keeper and he is a big-enough character to live with that. We are not putting any blame on him at all, we are blaming the pitch.
"It got a bobble and bounced over his foot. These things happen in football."
Blackburn: Friedel, Neill, Todd, Mokoena (Nelsen 52), Matteo, Emerton (Reid 71), Savage, Thompson, Tugay, Pedersen (Stead 71), Johnson.
Subs Not Used: Enckelman, Gallagher.
Goals: Watson 21 og, Johnson 27, Matteo 51.
Colchester: Davison, Stockley, Baldwin, Brown, Hunt (Chilvers 55), Halford, Danns, Watson, Johnson (Keith 79), Fagan, Williams (Ndumbu-Nsungu 58).
Subs Not Used: Gerken, Cade.
Ref: H Webb (S Yorkshire).