For the game, wear sunscreen. I went to a game recently and assumed I would be in the shaded part of the stadium, so I didn't wear any. Unfortunately, I was in the sun for three innings before the shade made it our way, and ended up getting my arms and neck burned. Also ended up buying a cap I'll probably never wear again. So, dress accordingly.
jays4life19 is also right about the food, it's really overpriced, and mediocre. You're better off getting a bite somewhere downtown. Although, I noticed the food trucks near the stadium are also a bit overpriced.
You should note that Union Station is currently under heavy construction, but in the station and outside it, so take that into consideration when getting to the stadium. Actually, most of downtown Toronto is under construction in some shape or form, so it's kind of a mess, at the moment.
Film festival is not a bad idea, but I think tickets are pricey, and you might not even be able to find a film that isn't sold out. You might be interested in Ripley's Aquarium, which is right next to the stadium. That's also pricey, but my sister went with her daughter and they loved it.