The loading image has a physical path instead of relative or literal… it’s in the calendar widget:
I’ve replaced the real path with the phrase {physicalPath} but you get the gist
<img id="ajax-loading-mini" src="F:\{physicalPath}/wp-content/plugins/event-tickets/src/resources/images/tribe-loading.gif" alt="loading..." />
<div class="tribe-mini-calendar-grid-wrapper">
<table class="tribe-mini-calendar" data-count="5" data-eventDate="2016-11-01" data-tax-query="" data-nonce="4496e7c5ac">
<thead class="tribe-mini-calendar-nav">
<tr>
<td colspan="7">
<div>
<a class="tribe-mini-calendar-nav-link prev-month" href="#" data-month="2016-10-01" title="October"><span>«</span></a> <span id="tribe-mini-calendar-month-0">November 2016</span>
<a class="tribe-mini-calendar-nav-link next-month" href="#" data-month="2016-12-01" title="December"><span>»</span></a> <img id="ajax-loading-mini" src="F:\{physicalPath}//wp-content/plugins/event-tickets/src/resources/images/tribe-loading.gif" alt="loading..." />
</div>
</td>
</tr>