Yes, landscape pages are allowed but the pagination must maintain consistency with the portrait pages in case the document is printed. This means you can either: a) rotate the image/table/figure and keep the page itself in portrait, or b) format the entire page in landscape. If you choose to do the latter, you will need to adjust the placement of the page numbers and manually rotate them to maintain consistency with the other pages.

A detailed explanation is available in this slideshow.

For assistance doing this in MS Word, please see this helpful guide.

* Update for MS Word 2016 (PC), for pagination in the footer:

1. Click on first landscape page. Insert > Edit Footer > remove “Link to previous” setting on all landscape sections and the portrait sections following them. Repeat for headers on each page as well (Insert > Edit Header > uncheck "Link to previous").
2. Repeat step 1 with your cursor on the first portrait page following the landscape page section.
3. Go to landscape page and delete the existing page number from the footer
4. Insert > Page number dropdown > Page Margins > Plain numbers > Border Left
5. Highlight number > Home ribbon > Use borders dropdown icon to select No Borders
6. In the Drawing Tools ribbon menu, click on Format > Text Direction > Rotate all text 90 degrees

Mac users: The instructions above apply the PC-version of MS Word only. There is a possible workaround described for the Mac version here. This involves using a text box in the footer of a landscape page, then inserting the PAGE field using Insert (Mac Menu bar) > Field > Page Number.