Continuity mistake: After the overdose in the car, James meets his social work to try and start again. He puts his paper cup on the desk. He drinks then from said cup. When she stands up, James' cup is fuller than before. (00:08:30)
Continuity mistake: James is counting pennies on the aptly named counter of the store. Take a look at the pile of money; there's one coin in particular which stands out, on top of the other flat ones, tilted to the left. A couple of shots later the coins slightly changed position, which is easy to tell noticing the change of position in that coin. (00:04:10)
Continuity mistake: The quantity of Kellogg's cereals in front of the cat's paws when James spots him vary between shots. (00:15:00)
Continuity mistake: James strokes the cat he just put on the counter in their first meeting. As he crouches, he puts his left hand above the right. When their eyes meet in the next shot (where incidentally the cat also looks right into the camera initially), the hands are swapped. (00:15:55)
Continuity mistake: During James and Bob's first meeting, in one early shot the box of cereals is on the counter next to the cat, while in the rest of the scene it's not there, nor it is supposed to since James gave his furry friend a lift but never picked the box up from the floor. (00:16:00)