Board Thread:Questions and Answers/@comment-36489727-20180806183842/@comment-1327106-20180806223825

I assume you mean what happened in the first episode of Season 3.

What the anime cut out is that Hange is testing the limitations of Eren's Titan and his transformations. When his transformation fails, that is actually his third transformation in the the span of a few hours.

During the first transformation the team learns that Eren can follow simple instructions and can even write in his Titan form. However, he cannot talk. After about an hour he became unresponsive and exited his Titan normally.

After resting a bit Eren does a second transformation, but this time he's smaller, cranky, and can't follow instructions.

The third transformation is all you see in the anime. Eren fails to completely transform, his bottom half is hanging out, and he's kinda melted into in his Titan.