In the review page, I sometimes don't see the bar that shows more of the question associated to an answer. For example, I was looking at https://english.stackexchange.com/review/first-answers?s=1&pagesize=50&filter=month, and this is what I saw after I expanded two answers (the image is a link to the full resolution image):
In the second answer, the bar is barely visible, as if it was shown disabled.
I was reviewing the answers to find answers that were not answers; the delay between expanding an answer and the other has not been more than 30 seconds (the time of reading the answer to see if it was another question).
In this case, the bar is shown different for just an answer, while in other cases, the bar is shown in the same way for all the reviewed answers.
The screenshot has been taken from Safari 5.1.2 running on Mac OS X 10.7.2.