This is only minor but the reply arrow in chat points right (see image here).
I would have expected it to point left, like the enter button and other replies, e.g. in Outlook.
Why is this?
The arrow to initiate a reply goes down, then right.
This is to counter the arrow used on the replying message, which goes up, then left, shown below.
Basically, it goes right to illustrate that "This is where I'm going to put my reply", with the right-directional arrow indicating thus "This is where my reply comes from". Grouping them together, you'd get a linking loop that symbolizes the connection between the reply and its origin message.