Code to exclude the single event we're viewing from the events list on the widget.

zewpgists_filter_tribe_events_widget.php

<?php
/*
 * Code to exclude the single event we're viewing from 
 * the events list on the widget.
 * 
 * Notes: 
 * - Only works with the Events Calendar plugin (Modern Tribe).
 * - 'zewpgists_' is a prefix for all my gists. Replace with your own.
 *
 */


add_filter( 'tribe_get_list_widget_events', 'zewpgists_exclude_single_from_widget' );

/**
 * Exclude the current event from the widget list
 *
 * @param array  $events Array of event posts.
 * @return array         Filtered array.
 */
function zewpgists_exclude_single_from_widget( $events ) {

	if ( is_singular( 'tribe_events' ) && $events ) {

		$unset = -1;
		global $post;
		$exclude = $post->ID;

		foreach ( $events as $key => $event ) {

			if ( $exclude === $event->ID ) {
				$unset = $key;
				break;
			}

		}

		if ( $unset >= 0 ) {
			unset( $events[ $unset ] );
		}

	}

	return $events;

}