The Doctor had hidden the posion he was looking at the paniced people "Oh what a shame." he said playing along still. He knew that as soon as the flowers were fed the posioned food it would only get worse.
He knew the people wouldn't work out who had done it.
The 11th Doctor winced and checked his injury, there was still moments it hurt. The excitement of what was going on had almost made him even forget about his injuries. He was shaking and looking around.