Since Comic-Con is just around the corner, SDMTS has released information regarding trolley service during the event.
To see the hours be sure to visit the SDMTS website. They announced limited edition Comic-Con passes as well:
This year, MTS is selling special commemorative Comic-Con day passes. These commemorative Comic-Con day passes do not require a Compass Card and can be purchased at select Trolley stations with ticket booth sales (see dates and times below). If you’d like to purchase a commemorative pass before July 17, you may do so at The Transit Store. You may also purchase regular 1–4 day passes from Ticket Vending Machines at Trolley stations. Ticket Vending Machines accept cash and credit/debit cards.