Word is able to format footnotes in columns, even if your body text does not use columns at all!

Or you may have a body text in 2 columns and your footnotes in 4 columns. Note that this is possible in footnotes only, you cannot have columns in end-notes.

To take advantage of this feature you have to save your document in docx format, as most Word users do anyway. Then go to the Footnotes dialogue and play with the Footnote layout option.

The docx format may be sometimes a little slower, but it provides increased security and more features such as better editing and higher fidelity of images, features not available in the formerly official doc format.