She then uses a doorjamb to brain Buck, the skeezy orderly who had been pimping out her comatose body, and steals his keys. Because the muscles in her legs have atrophied from disuse, she has to ride a wheelchair to escape, and the Bride rolls around the parking garage until she finds Buck's truck, then crawls inside. He won't mind, since he's now dead and all.
She would have taken his shoes, too, but they were too small.
As you can see, the Bride spends over half a day lying in the truck before her legs start working again and she is able to drive it the hell out of the garage.
So ... was Buck the only person working at the hospital that night? In the span of 13 hours, did nobody discover two fresh bodies lying in the middle of a suddenly missing coma patient's room? There must have been a shift change at some point -- at the very least, Buck's absence would have been noted, and we have to believe that a patient in the Bride's condition would be monitored pretty closely. When he didn't show up for roll call or respond to pages, and when they saw no updates on the Bride for the past half-day, hospital staff presumably would have sent someone to both look for him and check on her. Honestly, somebody should've tripped over those dead guys within 10 minutes of the Bride making it to the garage.
"Hey, this isn't where we store these."