Removing the space before note in post text

I’m similarly troubled. How do I get rid of the space?

You’ll have to edit the plugin. Change this (on the line that starts with return):

function shortcode( $atts, $content = null ) {
                global $id;
                if ( null === $content )
                        return;
                if ( ! isset( $this->footnotes[$id] ) )
                        $this->footnotes[$id] = array( 0 => false );
                $this->footnotes[$id][] = $content;
                $note = count( $this->footnotes[$id] ) - 1;
                return ' <a class="simple-footnote" title="' . esc_attr( wp_strip_all_tags( $content ) ) . '" id="return-note-' . $id . '-' . $note . '" href="#note-' . $id . '-' . $note . '"><sup>' . $note . '</sup></a>';
        }

to this:

function shortcode( $atts, $content = null ) {
                global $id;
                if ( null === $content )
                        return;
                if ( ! isset( $this->footnotes[$id] ) )
                        $this->footnotes[$id] = array( 0 => false );
                $this->footnotes[$id][] = $content;
                $note = count( $this->footnotes[$id] ) - 1;
                return '<a class="simple-footnote" title="' . esc_attr( wp_strip_all_tags( $content ) ) . '" id="return-note-' . $id . '-' . $note . '" href="#note-' . $id . '-' . $note . '"><sup>' . $note . '</sup></a>';
        }

Just remove the space before the opening of the <a> tag.

Thanks Grant for posting a solution. I will try that.

It’s a shame it’s not baked into the plugin, as this means that every time we upgrade we’ll have to edit this file.

Yes, this works. Thanks again!