In the scene where Trish has been secured by a chain to a vertical metal post by Malcolm, the chain is simply wrapped around the post. Trish could simply walk around the post therefore lengthening the chain allowing her to grab him or an object.
Detective Costa reminds the officers to read Sallinger his Miranda Rights. It is a myth that Miranda Rights must be read immediately upon arrest. They only need to be read before interrogating a suspect. Typically this is done at the police station.