Wilder was unhappy with Town's second-half performance during Saturday's pre-season friendly at Sixfields, which Orient edged 1-0 courtesy of Bradley Pritchard's 59th-minute goal.
"I was really pleased with the first-half performance, because Leyton Orient are a quality team," said Wilder.
"It was always going to be a tough test against them, and I was really pleased at half-time, but in the second half we fell away. There is a lot of work to be done in the next couple of weeks.
"So I have got mixed emotions about the match, and maybe this is a little bit of a wake-up call because the players have been excellent in pre-season.
"They have been good in everything they have done, but we dropped our standards in the second half.
"We weren't positive enough in our play, we went backwards and sideways, and didn't play at the tempo and intensity we have done for the majority of pre-season.
"So this is a bit of a wake-up call, but we still have two weeks of pre-season to go to tighten ourselves up a little bit, and we will get ourselves going again on Monday."