In a by-election littered with bizarre moments and triggered by an MP who quit Parliament before he could be kicked out, it was somewhat fitting that the Darling Range campaign drew to an end with a horse named Fiasco.

As Labor candidate Tania Lawrence and the Liberals' Alyssa Hayden spent the morning handing out how-to-vote cards at the Byford early polling centre, One Nation's Rod Caddies was down the road employing a more unconventional method to get his message out.

Atop his horse Fiasco, Mr Caddies juggled the reins and a campaign placard emblazoned with his face alongside that of leader Pauline Hanson as he rode alongside one of Byford's busiest roads, urging locals to vote for him.

Darling Range One Nation candidate Rod Caddies hoped his horse would help him grab some last-minute headlines. ( ABC News: Jessica Strutt )

"I think the horse's name ties in well with what's gone on — people think the whole thing's a fiasco, so it sort of suits the moment," Mr Caddies said.

Mr Caddies was looking forward to the presence of Ms Hanson adding what he dubbed her "celebrity status" to the final hours of his campaign, but even her arrival in Perth ended up being a bit of a fiasco.

She was scheduled to hold a media conference when she touched down, but it was cancelled at the eleventh hour after issues with flights and rescheduled to much later in the day.

The by-election was called after the resignation of Labor MP-turned-independent Barry Urban, whose extensive web of lies about his qualifications and police service history were ultimately exposed.

One more Labor fiasco before polling day

Labor spent most of the early part of the campaign dealing with its own fiasco, after doubts were raised about the education credentials of its first Darling Range candidate Colleen Yates.

Ms Yates ended up pulling out of the race and since then, Premier Mark McGowan has stuck tight to Labor's second candidate choice, Tania Lawrence.

But an incident involving his Water Minister Dave Kelly had the potential to turn Labor's final day of campaigning into yet another fiasco.

Overnight, the ABC had revealed WA Nationals Leader Mia Davies had made a formal complaint to Speaker of the Legislative Assembly about Mr Kelly over claims he "feigned a head butt" toward her while she spoke in Parliament on Thursday.

Parliamentary vision does not show Mr Kelly making such a gesture, but the footage is inconclusive as he does not appear in the frame the whole time.

Sorry, this video has expired Footage inconclusive after 'feigned headbutt' complaint against WA Minister

The Premier wasn't about to let the incident derail his high-stakes fight for the seat of Darling Range, however, and when quizzed about the allegations against his minister, went on the attack.

Mr McGowan lashed out at Nationals MP Vince Catania — a former Labor MP — who had called on Mr Kelly to apologise to Ms Davies, saying Mr Catania had a "record of untruthfulness as long as your arm."

"I'm not treating it at all seriously and I think it's fabricated," Mr McGowan said.

"I was there, I saw nothing. I watched the video, there's nothing.

"Dave Kelly says nothing occurred and it's Vince Catania who launched the attack. It's muck-raking on the eve of a by-election."

Labor 'good at bullying'

But the Liberals weren't letting the issue go away that easily.

Out on the hustings, Ms Hayden said Labor had form for allowing its male MPs to behave inappropriately towards women.

Ms Hayden says Labor has a record of male MPs intimidating women. ( ABC News: Eliza Laschon )

"Another Labor member of Parliament, male senior minister, intimidating a female in the workplace," Ms Hayden said.

"No matter where you are, you should not intimidate women in the workplace, it's as simple as that.

"This just shows Labor are good at bullying and standover tactics."

No doubt voters in the electorate can't wait for the close of polls tomorrow night, which will hopefully draw the final curtain on the whole Darling Range by-election fiasco.