Wilder felt his team had been drained by the miles they had travelled with away cup ties at Accrington and Plymouth, and last week's tragic death of former Oxford player Mitchell Cole at the age of 27.
After the teams, and spectators, staged a minute's applause for Cole before kick-off, Adam Mekki cancelled out Adam Chapman's first-half strike to earn the Shots a point.
Wilder said: "We're disappointed we didn't get all three points, but it's been a hell of a week.
"We've been travelling hundreds and hundreds of miles and the players have gone through a lot this week - they're human beings. The last 15 minutes the boys were out on their feet.
"We've not done enough to win this game, there wasn't enough quality or energy from us. We should have held on but we got pushed back.
"We needed that second goal to give us a bit of breathing space. But we didn't keep the ball well enough at the top of the pitch, or pass it well enough.
"The quality wasn't there, but if people give us a bit of leeway after what the players have gone through, I think that's only fair. There was an unbelievable amount of tired legs and tired bodies out there."
Oxford midfielder Simon Heslop was sent off for a professional foul on Mekki in the last minute.
But Wilder said: "I didn't think it was a sending-off, it was a booking. But then I didn't think it was a booking for Sean Rigg for diving in the first half either."