The hosts led by two goals at the break courtesy of Bale's early header and a James free kick.
Karim Benzema made it 3-0 early in the second period, before James scored Real Madrid's fourth in the 50th minute.
Here, Sports Mole has dissected the 90 minutes of action in Madrid.
On target: 11
On target: 1
Was the result fair?
There is little doubt that Real Madrid deserved to run out convincing winners on their own patch. After a disappointing draw with Sporting Gijon last week, Rafael Benitez would have wanted a fast start from his side and that was indeed the case as Bale scored with less than two minutes on the clock. In fairness to Betis, they managed to resist a host of pressure that followed and indeed cause some problems of their own, but when James made it 2-0 five minutes before the end of the first period, it was always going to be a tough ask for the visitors to respond. Two more goals arrived in the opening five minutes of the second period and from that point forward, it was very much a damage limitation exercise.
Betis did have the chance to cut the deficit to three goals just after the hour when Raphael Varane was adjudged to have felled Castro inside the box, but the experienced forward could not beat Navas from the spot. There were not bundles of chances from that point forward, but there was time for another goal as Bale scored his second from distance. When big scorelines occur, a case can usually be made that it was a little harsh on the receiver, but Betis can have little complaints here. Real Madrid had 21 attempts in total - 11 of which were on target. Betis, on the other hand, only managed one attempt on target throughout the 90 minutes. It was a very strong performance from a rampant Real Madrid outfit.
Real Madrid's performance
Benitez made two changes to his XI at the Bernabeu, with James and Benzema coming in for Isco and Jese Rodriguez, who both started the away draw at Sporting Gijon last week. As mentioned, the Spaniard would have wanted a fast start to the match and that was indeed what occurred. In truth, the hosts could have been three or four goals ahead inside the opening 10 minutes, but Benzema and Ronaldo were both guilty of missing opportunities. The tempo of the match dropped as the first period developed, but a quite stunning free kick from James made it 2-0 in the 39th minute, which settled the players and those in the stands. It was a strong first-half performance rather than an entirely dominant one, but it got much better in the early stages of the second period. Benzema made it 3-0 with a close-range header in the 47th minute, before James collected a sharp pass from Toni Kroos and volleyed home just three minutes later.
Ronaldo was desperate to get his name on the scoresheet and came close just before the hour, but the Portuguese could not win his personal battle with Betis goalkeeper Antonio Adan. A somewhat clumsy challenge from Varane handed Betis the chance to score from the penalty spot in the 61st minute, but Navas denied Castro with a smart save. Quite whether the Costa Rican will be Real Madrid's first-choice stopper by the end of the transfer window, however, is currently unknown. Ronaldo and Sergio Ramos both came close to adding to the scoreline late on, but it was Bale's long-range strike via the post that made it 5-0. The only real disappointment of the night was the fact that Ronaldo could not get among the goals, but James and Bale in particular were both excellent. It has been questioned whether Benitez will allow his team to play expansive football this season - well there can be no criticism following this five-star performance.
Real Betis' performance
After picking up a late point against Villarreal last weekend, Betis would have entered this match full of confidence. That said, the Andalusian side had won just one of their last 23 away La Liga games entering this match and had not beaten Real Madrid in their last 12 meetings. A positive start would have been on the agenda, but as mentioned, Bale's header inside two minutes made it a very tough task. In fairness to the visitors, they managed to resist a second goal and caused some problems of their own as the first period developed. Castro had the chance to level the scores in the 30th minute after good work from Juan Manuel Vargas in a wide position, but the striker took too long and Navas was on hand to claim. Entering the interval 1-0 behind would have been far from the end of the world, but James' free kick five minutes before the break and a disastrous five-minute spell in the second period saw them quickly fall 4-0 behind.
It would have been nice if the away supporters had something to cheer after vocally backing their team throughout the match, but Castro missed from the penalty spot after being felled by Varane. Not too much occurred for the final 30 minutes or so, but Adan did produce some excellent saves to keep the score down, until Bale made it five late on. Pepe Mel would have seen some positives throughout the match, but the fact that they only managed one attempt on target, which was the penalty, will be a concern. In-demand youngster Dani Ceballos was given the chance to start in the final third, but the teenager struggled to make his mark, while Francisco Molinero struggled out of position at left-back and was hooked at the interval. Whether Betis remain in La Liga this season is not going to depend on their results at places such as the Bernabeu, however, and it is important that they recover from this defeat as soon as possible.
Sports Mole's man of the match
James Rodriguez: The Colombian had a quite wonderful game for the hosts. Injury prevented him from starting last week, but the attacker produced two goals and one assist at the Bernabeu. James first set up Bale in the second minute, before scoring a stunning free kick and a wonderful over-head effort. Bale was also excellent, but Colombia's World Cup star was on a different level in Madrid.
Betis boss Mel would have wanted a strong start from his team to the second half, but with 50 minutes on the clock, the visitors were 4-0 behind. Benzema's goal was more good play from Real Madrid than bad defending, but Betis did not push out for the home side's fourth and poor defending at this level will almost always be punished.
Referee Alejandro Hernandez had a busy game at the Bernabeu - issuing six yellow cards in total. Real Madrid can count themselves a little unfortunate to have conceded a penalty in the second period, with Varane's contact on Castro minimal to say the least. The hosts had a couple of penalty shouts of their own, but Hernandez was right to shake his head.
Real Madrid: Los Blancos return to La Liga action away to Espanyol on September 12.
Real Betis: Next up for Betis is a home league game against Real Sociedad on September 12.