MCAT is a screening mechanism combined with GPA, personal statement and CV to screen candidates get admit to medical school.
To get into residency programs, there are several process. USMLE (United states medical license exam, step I), test the first two years of clinical science core classes. The score is important to rank the candidates, and recommendations letters, interviews for residency, personal statement. CV etc.
So, basically as a potential medical student, there are screening and ranking processes every 3 years or so.
Non-MCAT programs DO NOT have any bearing on residency applications, but the strength of the candidates during medical school and making the best use of residency matching algorithm will determine our residency match.
However, there are more tricks and tips in the residency applications.