My illustration's paths are slightly off when making a reflected copy?

I would like to reflect my illustration accross a vertical axis but I am having trouble with the paths being slightly off when the reflection is made?

( I also had this issuew when making a copy but I decide to delete the copy, restart illustrator, and the problem seemed to go away.)

Here is the original:

Here's my reflected copy:

These are the imperfections that don't carry over identically when the original piece is mirrored:

I am not entirely sure as to why this problem happens.