It was not so much the size of the defeat as the fact that early in the second half, when they were trailing only 4-0 by virtue of an early try by Kevin Iro, he believed his side could win.
"That was when we should have grabbed the game by the scruff of the neck," Goodway said. "But we didn't ask enough questions of the opposition."
Mistakes gave Mariners' stand-off Scott Hill the chance to run in two tries inside eight minutes, then winger Gavin Thompson scored twice. Finally, Willie Poching scored on the siren.
Goodway's Hunter counterpart, Graham Murray, said he had trouble motivating his players.
"When we played Brisbane and Canberra there was a great atmosphere - great anticipation," he said. "It's different when you are hot favourites. But you can't run on to the field expecting to win. When you do that, you are likely to come unstuck."
Graham Steadman kicked a goal for the 2,000th point of his career, but it was not enough for Castleford as they were outfought 24-14 by Perth Reds.
Steadman was also involved in the game's turning point, when his disallowed try proved crucial. The blow came in the 35th minute when Perth led 14- 0. A dropped ball saw Steadman race 60 metres to score only to be denied by the video referee. On close inspection, the ball was dropped when Dean Sampson's arm touched it.
Perth scored from the ensuing scrum, when a back-flip pass by John Wilshere found Matt Geyer, who ran 25 metres to touch down. Shaun Devine added a touchline conversion to give Perth a 20-0 half-time lead.
Castleford held the Reds for the opening 22 minutes until a freakish kick by Devine rebounded from Brendan Tuuta straight into his arms, and he ran in under the posts. He then converted for a 6-0 lead.
Mark Geyer, back from his second suspension this season, scored in the 27th minute. Devine converted then followed up with a 33rd-minute penalty.
In the 45th minute, Perth replacement Peter Shiels was sent off for using his elbow on Lee Harland, and Castleford took advantage when a Steadman kick found the hands of Jason Roach, who touched down.
Devine added a penalty, but the Tigers hit back with two tries in three minutes. The first came in the 70th minute when Danny Orr supplied Jason Flowers, who scored. Jason Critchley then raced 40 metres to touch down.
Time beat Castleford in the end, though, Devine ending the scoring with a 78th-minute goal.