An all-Championship clash went the way of MK Dons who netted a winner in the 108th minute of the game to ensure their passage to the 3rd Round.
With Cardiff in action against Nottingham Forest this weekend, Slade feels that ties at this stage should be decided on penalties if the scores are level after 90 minutes.
Quoted on Wales Online he said: "A lot of managers would agree with me.
"Both managers would have been happy to decide this tie on penalties and not have extra-time. Some players will have to go out again on Saturday and Forest will be delighted we have had a tough 120 minutes."
Slade did, however, complete a new signing on Wednesday with Romanian defender Gabriel Tamas signing a one-year contract after a successful trial period.