I made a website for a fairly reputable company a while back and I only had about a week to do it so I used Wix. Is it worth mentioning in interviews or anything or is it useless considering its Wix?

Personally If I was interviewing you I probably wouldn't think much of it either way. Good or bad. If you did any custom work that wix did not do out of the box i would emphasize that. That being said I can see some hiring managers being more wary of it then I am.