Amtrak is invariably late, coming thru the Dakota oil fields. BNSF owns the line which Amtrak runs on and the oil runs take priority. I have ridden Amtrak plenty of times and love rail travel. I just don't set my watch to Amtrak time like I could do on trains in Europe/Scandinavia.
Don't park downtown. $16-20. Plenty of parking along Greenline (yes, it runs at all hours). Raymond stop, Lexington (my parking area), midway between Target Field and Union Station (last stop on Greenline). Park on side street north of University (~1100 block of Charles). 1/2 hour to Target; 20 min to Union Station.
Give a yell here or message me if you have more questions.
Ticket is good for 2 hours if you have to scoot out of game early.