Maya and Joshua are said to have a 3 years age gap, however the gap is actually 2 years: Joshua is born on Valentine's day 1999 (Boy Meets World: My Baby Valentine) and Maya is born in January 2001 (Girl Meets World: Girl Meets Master Plan).
When Cory holds Riley yo the class it shows from outside the class that there's nobody inside, but the next scene inside the class that there's students there.