SINGAPORE: Five talking points from the Singapore Grand Prix, won by Ferrari's Sebastian Vettel:

1. Who left the gate open?

Organisers were facing serious security questions after a spectator wandered onto the circuit and down the track, prompting a double-take from race-leader Sebastian Vettel who thought he was seeing things.

While it wasn't clear how or why the fan was on the track, pictures on social media showed a gate to the street circuit open and unguarded.

A 27-year-old man was arrested and “is assisting police with investigations”, a statement said.

2. Technical glitch

Engineers wondered whether gearbox problems in Singapore were caused by electrical or magnetic interference from a nearby subway line.

“Odd numbers” on sensors were seen when the cars passed near the Anderson Bridge section, McLaren's technical boss was reported as saying.

The team was so concerned that it added “electrical shielding” to its cars and tweaked their software.

3. The kid’s all right

Teenager Max Verstappen's reputation continues to grow, to the point where he is now able to challenge his bosses at Toro Rosso — and win.

The 17-year-old had a nightmare start when he stalled on the grid and had to rejoin the race a lap behind everyone else.

After impressively carving his way back up to eighth, Verstappen was told to yield his place to team-mate Carlos Sainz, to which he replied: “No!” Verstappen's reaction was vindicated when team principle Franz Tost said he was right to ignore the order.

4. Red faces at Ferrari

The mechanics at Ferrari will have sore heads and red faces on Monday after their post-race antics earned a stern reprimand.

According to reports, over-zealous Ferrari team members shoved past security and knocked barriers to the ground as they rushed to celebrate with race-winner Vettel.

A team official was summoned to the stewards and promised to send written apologies to those affected.

5. ‘Crashdonado’ keeps his spot

Jenson Button can be forgiven a wry smile when he hears Lotus have renewed Pastor Maldonado's deal for 2016.

The McLaren driver called Maldonado's driving “very strange” after a collision with the Venezuelan which ended his race.

“He hasn't changed, and he won't ever change,” said Button.

The Lotus driver has been dubbed “Crashdonado” by his detractors, and is the subject of a website called hasmaldonadocrashedtoday.com.