Posh led 1-0 at the break thanks to a Jonson Clarke-Harris goal, but lost their way in the second perios and let the hosts back in with a penalty after a goalkeeping mistake and a bit of dozy defending.
Mostly, one eleven played for around 55 minutes until Darren Ferguson withdrew them early in favour of a second originally scheduled to play the final 30.
Nicholas Bilokapic and Peter Kioso appeared in Posh colours for the first time.
The players are listed below in the order of the side that began the game followed by the one that ended it.
1. Peterborough United player ratings vs Colchester
Will Blackmore's error proved to be the main talking point of the game. Photo: Joe Dent
2. NICHOLAS BILOKAPIC
Little to do but dealt with a few balls into the box well. Highlight was a skilful turn under pressure to show what he can do with his feet 6.5. Photo: Joe Dent
3. JAMES DORNELLY
Only played 30 minutes as part of a planned change, didn't shy away from any physical battles. 6. Photo: Joe Dent
4. EMMANUEL FERNANDEZ
Lacked sharpness, first touch looked off and often got caught out of position too far upfield. 5 Photo: Joe Dent