When Jane goes pounding on the door on the 4th floor, we see her through the peephole. The first two shots show her standing in an empty hallway, then when she's done pounding and starts to turn away, there are suddenly several bags of garbage around her.
When Albert is trying to find Jane in her apartment, he looks into the living room where a cigarette is clearly smoking in an ashtray. While running for her life from Albert, she would not have had time nor the inkling to light a cigarette. This was a recycled scene from earlier in the film when Greg was visiting her.
As Jane stomps on the floor of her apartment trying to make the hanging plaque fall on Collins, glass is present and her foot is bleeding. After the plaque falls, Jane tries to retrieve the knife Collins dropped. The soles of her feet are visible and there is no blood.