From my perspective you have got half the story but not the whole one. The LE took the gas cans TWICE to do testing on them. The first time they came back with a piece of tape that GA said he put on it - very neat and tidy. The second time they came back the tape was all askew and not in the manner that GA would have done it.
During the trial, George had to adhere to his Depo. Baez was trying to trick him (or make him angry and lose his temper) by showing him pics of the other time LE took the gas cans, rather than the one the picture was about, and George knew it. That's why he was acting as twitchy as he was.
He was answering the question Baez asked him and looking at the wrong picture. I'm surprised more people didn't pick up on that.