Editor’s note: Inc.com columnist Alison Green answers questions about workplace and management issues–everything from how to deal with a micromanaging boss to how to talk to someone on your team about body odor.

A reader writes:

I have a job interview lined up that I’m really looking forward to. I like the organization, it’s an appropriate step up from my current job, and all that good stuff. So I did all my research and prep, took the day off work, put on my interview clothes, and headed off – only to discover that I had the day wrong. The interview was actually scheduled for a week later!

So aside from the fact that I feel like the world’s biggest bonehead, can you take a guess at what they might be thinking at their end? Is this the kind of thing that can be mitigated with an “I’m mortified and this is clearly a terrible mistake that is in no way a reflection of how I might perform on the job” type email? Or is it likely to be seen as a strike against me from the beginning, making me look really disorganized and not at all like a good candidate for the position?

I have sent the apology email already, and of course I’m going to go to the interview and be a superstar on the correct date as well. But if you could give me some insight into how big a deal this might be, I would appreciate it!

Well … It’s not good. It’s not a deal-killer in and of itself, but it’s not great.

The concern on the employer’s side is whether you’re overly cavalier about details. If they hire you, are you going to forget about scheduled calls with clients or think a report that’s due tomorrow is due a week from now?

That might seem like an overreaction to a single mistake, but employers have very limited data about you during a hiring process, so they’ve got to go on what they do know — and given that limited data, small mistakes can take on disproportionate importance.

Here’s what happens in a hiring manager’s head when a job candidate makes a mistake that might be no big deal in someone they knew better: “We clearly confirmed the interview for next Tuesday, but somehow she showed up today. This might be out of character for her. After all, everyone screws up occasionally. But if I ignore this possible red flag and hire her, and then she turns out to be scattered and bad with deadlines, I’m going to be kicking myself for not having paid attention to this sign now.”

And the reality is, there’s reason to think that way. When I’ve ignored small red flags in hiring because they seemed too minor to base a hiring decision on, they’ve pretty much always come back to bite me. After having that happen enough, hiring managers learn to put weight even on small signs, because, ultimately, you’ve got to go on what you see, not speculation about what might be.

So, what does this mean for you now? It probably doesn’t mean that you’re out of the running, but the bar is going to be higher for you now than it was before, because you’ve got to overcome the concern that this inserted into the process. Sending a mortified email was one step toward doing that. In addition, I’d proceed as if you have no room for error from this point, and you want to find ways to demonstrate that you’re highly, highly on the ball. So that means things like not being even a minute late when you show up for the actual interview … and if you promise to send materials later (like a reference list or writing sample), send them that same day … and if your references can reasonably be expected to say good things about your reliability and attention to detail, prompt them to do … and so forth.

Will it be enough? It could be! You’ve got nothing to lose by trying, certainly.

(And hey, at least you didn’t get it wrong by a week in the other direction and totally miss the day it was scheduled for. That would generally be a deal-breaker right then and there.)

Want to submit a question of your own? Send it to alison@askamanager.org.