Truncate the details parameter of Google calendar link to 1000 characters.

tribe-google-calendar-event-strip-tags.php

<?php

//Add the following to your theme's functions.php
add_filter( 'tribe_google_calendar_parameters', 'tribe_google_calendar_link_modify', 10, 2 );
function tribe_google_calendar_link_modify( $params ) {
	$mod = urldecode( $params['details'] );
	$mod = strip_tags( $mod );
	$mod = str_replace( ' ', '+', $mod );
	unset($params['details']);
	$params['details'] = $mod;
	return $params;
}

?>

tribe-google-calendar-link-modify.php

<?

//Add the following to your theme's functions.php
add_filter( 'tribe_google_calendar_parameters', 'tribe_google_calendar_link_modify', 10, 2 );
function tribe_google_calendar_link_modify( $params ) {
	$mod = substr($params['details'], 0, 1000);
	unset($params['details']);
	$params['details'] = $mod;
	return $params;
}

?>

This hack is no longer required. It is written in to ECP 2.0.7.

Updated to work with ECP 3.2