根據 US Patent Office，

Use of the "™", "^SM" and "®" Symbols

Anyone who claims rights in a mark may use the TM (trademark) or SM (service mark) designation with the mark to alert the public to the claim. It is not necessary to have a registration, or even a pending application, to use these designations. The claim may or may not be valid.

The registration symbol, ®, may only be used when the mark is registered in the PTO. It is improper to use the registration symbol at any point before the registration issues.

也就是說，沒登記的話可以用 ™（也只能用 ™） ，有登記才可以用 ® (在美國是這樣，其它國家就不清楚了…)

再根據 Mozilla® Trademark Policy，

The Mozilla trademarks include, among others, the names Mozilla®, mozilla.org®, Firefox®, Thunderbird™, Bugzilla™, Camino®, Sunbird®, Seamonkey®, Foxkeh™ and XUL™, as well as the Firefox logo, Thunderbird logo, SeaMonkey logo, Camino logo, Foxkeh logo and the Mozilla red lizard logo. As Mozilla registers others, it will update this policy.

所以…好像用「Mozilla®」比「Mozilla™」正確…